U.S. patent application number 11/749526 was filed with the patent office on 2007-11-15 for gateway system to interface different communication networks.
This patent application is currently assigned to Sprint Communications Company L.P.. Invention is credited to Jean M. Christie, Joseph Michael Christie, Joseph S. Christie, Albert Daniel DuRee, Michael Joseph Gardner, Tracy Nelson, William Lyle Wiley.
Application Number | 20070263644 11/749526 |
Document ID | / |
Family ID | 24379843 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070263644 |
Kind Code |
A1 |
Christie; Joseph Michael ;
et al. |
November 15, 2007 |
GATEWAY SYSTEM TO INTERFACE DIFFERENT COMMUNICATION NETWORKS
Abstract
A first communication network transfers a signaling message for
a call to a second communication network. The signaling message
indicates a first identifier that represents a connection through
the first communication network to the second communication
network. The second communication network processes the signaling
message to select a second identifier. The first communication
network transfers a user communication for the call to the second
communication network. The user communication has a header
indicating the first identifier. In response to the first
identifier, the second communication network modifies the first
identifier in the header to the second identifier. The second
communication network transfers the user communication to a
destination node in response to the second identifier in the header
of the user communication.
Inventors: |
Christie; Joseph Michael;
(San Bruno, CA) ; Christie; Joseph S.; (Mt.
Pleasant, PA) ; Christie; Jean M.; (Mt. Pleasant,
PA) ; DuRee; Albert Daniel; (Independence, MO)
; Gardner; Michael Joseph; (Overland Park, KS) ;
Nelson; Tracy; (Shawnee Mission, KS) ; Wiley; William
Lyle; (Olathe, KS) |
Correspondence
Address: |
SPRINT
6391 SPRINT PARKWAY
KSOPHT0101-Z2100
OVERLAND PARK
KS
66251-2100
US
|
Assignee: |
Sprint Communications Company
L.P.
Overland Park
KS
|
Family ID: |
24379843 |
Appl. No.: |
11/749526 |
Filed: |
May 16, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10686221 |
Oct 15, 2003 |
7239644 |
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11749526 |
May 16, 2007 |
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10119981 |
Apr 10, 2002 |
6683878 |
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10686221 |
Oct 15, 2003 |
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09392489 |
Sep 9, 1999 |
6529514 |
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10119981 |
Apr 10, 2002 |
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09123162 |
Jul 27, 1998 |
6026091 |
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09392489 |
Sep 9, 1999 |
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08594661 |
Feb 2, 1996 |
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09123162 |
Jul 27, 1998 |
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08568551 |
Dec 7, 1995 |
5825780 |
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08594661 |
Feb 2, 1996 |
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08238605 |
May 5, 1994 |
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08568551 |
Dec 7, 1995 |
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Current U.S.
Class: |
370/401 |
Current CPC
Class: |
H04L 2012/5626 20130101;
H04Q 11/0478 20130101; H04L 2012/563 20130101; H04Q 2213/13389
20130101; H04L 49/254 20130101; H04Q 2213/13102 20130101; H04L
49/3009 20130101; H04Q 2213/13176 20130101; H04Q 2213/13296
20130101; H04Q 2213/1338 20130101; H04L 2012/5672 20130101; H04Q
3/0025 20130101; H04L 49/255 20130101; H04J 3/125 20130101; H04Q
2213/1329 20130101; H04J 3/247 20130101; H04L 12/4608 20130101;
H04L 49/3081 20130101; H04L 2012/5619 20130101; H04Q 2213/13104
20130101; H04Q 3/0016 20130101 |
Class at
Publication: |
370/401 |
International
Class: |
H04L 12/46 20060101
H04L012/46 |
Claims
1. A method of processing a call from a first communication
network, the method comprising: in a call processor in a second
communication network, receiving a signaling message from the first
communication network wherein the signaling message indicates a
first identifier that represents a connection through the first
communication network to the second communication network; in the
call processor, processing the signaling message to select a second
identifier; in the call processor, transferring a control message
indicating the first identifier and the second identifier; in a
gateway in the second communication network, receiving the control
message; in the gateway, receiving a user communication from the
first communication network wherein the user communication has a
header indicating the first identifier, and in response to the
first identifier and the control message, modifying the first
identifier in the header to the second identifier; and transferring
the user communication from the gateway through the second
communication network to a destination node in response to the
second identifier in the header of the user communication.
2. The method of claim 1 wherein the second communication network
has a routing configuration and the first identifier in the header
of the user communication is not compatible with the routing
configuration.
3. The method of claim 2 wherein the second identifier in the
header of the user communication is compatible with the routing
configuration and wherein transferring the user communication
through the second communication network to the destination node in
response to the second identifier in the header of the user
communication comprises transferring the user communication through
the second communication network to the destination node based on
the routing configuration.
4. The method of claim 1 wherein the first communication network
receives the user communication with the first identifier in the
header from customer premise equipment.
5. The method of claim 1 wherein the destination node comprises
customer premise equipment.
6. The method of claim 1 wherein the destination node comprises
another gateway.
7. The method of claim 1 wherein processing the signaling message
to select the second identifier comprises processing a dialed
number in the signaling message to select the second
identifier.
8. The method of claim 1 wherein the gateway has single
input/output throughput.
9. The method of claim 1 wherein the user communication comprises
an asynchronous transfer mode cell.
10. The method of claim 1 wherein the call processor does not
include a switching fabric.
11. A second communication network to process a call from a first
communication network, the second communication network comprising:
a call processor configured to receive a signaling message from the
first communication network wherein the signaling message indicates
a first identifier that represents a connection through the first
communication network to the second communication network, process
the signaling message to select a second identifier, and transfer a
control message indicating the first identifier and the second
identifier; a gateway configured to receive the control message,
receive a user communication from the first communication network
wherein the user communication has a header indicating the first
identifier, and in response to the first identifier and the control
message, to modify the first identifier in the header to the second
identifier; and a routing system configured to transfer the user
communication from the gateway to a destination node in response to
the second identifier in the header of the user communication.
12. The second communication network of claim 11 wherein the
routing system has a routing configuration and the first identifier
in the header of the user communication is not compatible with the
routing configuration.
13. The second communication network of claim 12 wherein the second
identifier in the header of the user communication is compatible
with the routing configuration and wherein the routing system is
configured to transfer the user communication to the destination
node based on the routing configuration.
14. The second communication network of claim 11 wherein the first
communication network receives the user communication with the
first identifier in the header from customer premise equipment.
15. The second communication network of claim 11 wherein the
destination node comprises customer premise equipment.
16. The second communication network of claim 11 wherein the
destination node comprises another gateway.
17. The second communication network of claim 11 the call processor
is configured to process a dialed number in the signaling message
to select the second identifier.
18. The second communication network of claim 11 wherein the
gateway is configured with single input/output throughput.
19. The second communication network of claim 11 wherein the user
communication comprises an asynchronous transfer mode cell.
20. The second communication network of claim 11 wherein the call
processor does not include a switching fabric.
Description
CROSS-REFERENCES
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 10/686,221, filed on Oct. 15, 2003; which is a
continuation of U.S. Pat. No. 6,683,878, filed on Apr. 10, 2002;
which is a continuation of U.S. Pat. No. 6,529,514, filed on Sep.
9, 1999; which is a continuation of U.S. Pat. No. 6,026,091, filed
on Jul. 27, 1998; which is a continuation of abandoned U.S. patent
application Ser. No. 08/594,661, filed on Feb. 2, 1996; which is a
continuation-in-part of U.S. Pat. No. 5,825,780, filed on Dec. 7,
1995, which is a continuation of abandoned U.S. patent application
Ser. No. 08/238,605, filed on May 5, 1994; and which are all hereby
incorporated by reference into this application.
BACKGROUND
[0002] Current ATM communications systems may transport
communications traffic over switched virtual circuits (SVC) or
permanent virtual circuits (PVCs). SVCs are set-up and torn down as
requested--like telephone calls. PVCs are provisioned through an
ATM network and are used like a dedicated communications channel.
Aside from PVCs and SVCs, Permanent Virtual Paths (PVPs) and
Switched Virtual Paths (SVPs) are also available. The use of SVCs
or SVPs typically results in more efficient use of ATM bandwidth.
As is known, ATM communications paths are logically designated by
the Virtual Path Identifier (VPI) and the Virtual Channel
Identifier (VCI) located in the ATM cell header.
[0003] ATM cross-connect devices route ATM traffic by associating
virtual connections. A cross-connect associates two virtual
connections by changing the VPI/VCI of ATM cells from one virtual
connection to the VPI/VCI of the other virtual connection. For PVCs
or PVPs, these routes have been pre-provisioned. This means that
the routing configuration is set and remains static. Typically, a
cross-connect has multiple routing configurations that are stored
in memory. Network administration can select different routing
configurations, but changes are not implemented dynamically on a
call-by-call basis. In any event, the number of routing
configurations required to support call routing would be
prohibitively complex. In a provisioned cross-connect, the VPI/VCIs
in incoming cells are changed to pre-assigned VPI/VCIs.
[0004] SVCs and SVPs are handled differently. Since the VPI/VCIs
are set-up and torn down frequently, provisioned routing
configurations with pre-assignments of VPI/VCIs are not possible.
For SVCs and SVPs, the VPI/VCIs are dynamically selected in real
time on a call-by-call basis by an ATM switching function. The
switching function makes the selections by processing of
information in telecommunications signaling. An example of such
signaling is B-ISUP signaling.
[0005] Some ATM systems use pre-provisioned PVPs to connect the
network elements, and then dynamically select SVCs within the PVPs.
In this way, network elements can each be interconnected by PVPs to
form a flat architecture, and SVCs can be dynamically allocated to
maximize efficient use of bandwidth. In this environment, problems
are caused when one network is connected to another network.
Current signaling capability required by the switching function is
not able to handle high volumes of traffic. This impairs the
ability of separate networks to dynamically allocate SVCs between
multiple cross-connects on a call-by-call basis. As for the PVPs,
extensive administrative information must be shared to coordinate
all of the PVP provisioning between the two networks. An additional
coordination problem occurs with signaling between networks. When
networks interface at multiple points, signaling routes must be
defined so each interface point can signal the opposing interface
points.
[0006] One solution is to install complex ATM switches with full
signaling capability. At present, such devices are not readily
available at the quality and cost required for a robust and
cost-effective deployment. There is a need for a cost-efficient
system to interface between two ATM networks and alleviate the
problems described above--namely the coordination of PVPs and
SVCs.
[0007] Gateways are devices that interface different networks or
systems. They allow interconnection between different networks that
are not coordinated. Some examples are Internet Protocol (IP)
bridges and X.75 gateways. But, these systems are not able to
interface PVPs and SVCs of two ATM networks. These devices are not
capable to handle ATM. Additionally, they are not designed to
handle the dynamic allocation of connections required for SVCs.
Thus, an ATM gateway is needed to interface two ATM networks. This
ATM gateway must be able to handle the dynamic allocation of
VPI/VCI connection assignments required to support SVCs.
SUMMARY
[0008] A first communication network transfers a signaling message
to a second communication network for a call. The signaling message
indicates a first identifier that represents a connection through
the first communication network to the second communication
network. The second communication network processes the signaling
message to select a second identifier. The first communication
network transfers a user communication for the call to the second
communication network. The user communication has a header
indicating the first identifier. In response to the first
identifier, the second communication network modifies the first
identifier in the header to the second identifier. The second
communication network transfers the user communication to a
destination node in response to the second identifier in the header
of the user communication.
DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram of a version of the present
invention.
[0010] FIG. 2 is a block diagram of a version of the present
invention.
[0011] FIG. 3 is a block diagram of a version of the present
invention.
[0012] FIG. 4 is a logic diagram of a version of the invention.
[0013] FIG. 5 is a logic diagram of a version of the invention.
[0014] FIG. 6 is a message sequence chart for a version of the
invention.
[0015] FIG. 7 is a message sequence chart for a version of the
invention.
[0016] FIG. 8 is a message sequence chart for a version of the
invention.
[0017] FIG. 9 is a message sequence chart for a version of the
invention.
[0018] FIG. 10 is a message sequence chart for a version of the
invention.
[0019] FIG. 11 is a message sequence chart for a version of the
invention.
[0020] FIG. 12 is a message sequence chart for a version of the
invention.
[0021] FIG. 13 is a message sequence chart for a version of the
invention.
DETAILED DESCRIPTION
[0022] For purposes of clarity, the term "connection" will be used
to refer to the transmission media used to carry user traffic. The
term "link" will be used to refer to the transmission media used to
carry signaling. On the Figures, connections are shown by a single
line and signaling links are shown by double lines.
[0023] FIG. 1 depicts a version of the present invention. Shown are
signaling and control system 100, ATM system 120, ATM system 140,
and gateway 130. These components are connected by connections
160-161 and linked by links 150-152 as shown. Those skilled in the
art are aware that large networks have many more components than
are shown, but the number of these components has been restricted
for clarity. The invention is fully applicable to large
networks.
[0024] ATM systems 120 and 140 are known in the art. They typically
include ATM connections, cross-connects, and switches. Any source
of ATM cells is contemplated by the invention. At least one of the
ATM systems will have the need to control the VPI/VCIs of cells
entering the network. This is because the cells entering the
network have VPI/VCIs designated by the preceding network. These
VPI/VCIs are not necessarily compatible with the routing
configuration of the subsequent network accepting the cells. As
such, the VPI/VCIs must be modified to be compatible the new
VPI/VCI routing configuration. This is especially true if the ATM
network is handling SVCs without an ATM switch to process signaling
and select the proper SVCs in real time. If only pre-provisioned
cross-connects are used, the VPI/VCI in the incoming cell
effectively selects the VPI/VCI the cell will have when it exits
the cross-connect. If SVCs are to be dynamically allocated on a per
call basis through pre-provisioned cross-connects, a system is
needed to modify the VPI/VCIs to allocate SVCs before the cells
enter the cross-connect.
[0025] Gateway 130 provides this capability. Gateway 130 receives
ATM cells entering a network and converts the VPI/VCIs in the cells
so they are compatible with network routing configuration. Gateway
130 would modify the VPI/VCIs of cells entering ATM system 140 on a
call-by-call basis. This allows for the allocation SVCs. Gateway
130 could also operate in a two-way fashion. This means it will
modify the VPI/VCIs of cells entering ATM system 120 according to
ATM system 120 requirements, and it will modify the VPI/VCIs of
cells entering ATM system 140 according to ATM system 140
requirements. Gateway 130 is capable of modifying VPI/VCIs based on
control instructions from signaling and control system 100.
[0026] Signaling and control system 100 receives signaling passed
between the two networks. Typically, the signaling would be
Signaling System #7 (SS7) messages. As will be described in detail
later, signaling and control system 100 is able to receive and
process SS7 signaling to select the appropriate VPI/VCI for cells
entering a given network. It passes this information to the gateway
130 over control link 151. Control link 151 could be a bus, a data
link or a signaling link. Those skilled in the art will appreciate
various ways to couple signaling and control system 100 with
gateway 130. It is important to note that signaling and control
system 100 and gateway 130 do not comprise an ATM switch. Those
skilled in the art will appreciate from the following discussion
how these components can be constructed and operated without the
complexities and cost of an ATM switch. Another advantage is that
the gateway has single input/output throughput. This avoids many
problems ATM switches encounter with multiple input and output
ports. This also allows the gateway to concentrate traffic flowing
into a network. In other words, the gateway is able to reorganize
the traffic entering a network.
[0027] FIG. 2 depicts a version of the present invention. Shown are
gateway 200 composed of control interface 250, header mapper 210,
ATM label converter 230 and ATM interfaces 220 and 240. Connections
263 and 264 are ATM connections to ATM systems. Call/Connection
Manager (CCM) 270 is a version of signaling and control 100 from
FIG. 1. CCM 270 processes signaling and exerts control over the
gateway 200 via link 260. This link could be any means of
exchanging control information such as a signaling link, a data
link, or a bus arrangement. Links 261 and 262 provide signaling to
CCM 270. An example would be an SS7 link, but other means to
transfer signaling would be appreciated by one skilled in the
art.
[0028] CCM 270 is a processing system that receives and processes
signaling messages. CCM 270 processes the signaling messages to
select VPI/VCI assignments for gateway 200. In other words, it is a
call processor. It is different from a switch in that it does not
have a switching fabric, and it does not carry actual user traffic.
Typically, the processing is based on a dialed number, and can
include validation, routing, and billing. CCM 270 would be
functional to send control messages to the gateway 200. For call
set up, the control message would instruct gateway 200 to modify
the VPI/VCI in incoming cells to the VPI/VCI selected dynamically
by CCM 270. For call tear down, the control message would instruct
gateway 200 to disassociate the incoming VPI/VCI from the outgoing
VPI/VCI. This releases the bandwidth associated with the call. CCM
270 is discussed in detail below.
[0029] Control interface 250 is functional to receive control
messages and transmit status information. It could be a
conventional hardware/software interface. Header mapper 210 is a
logical table that contains the information associating incoming
VPI/VCIs with outgoing VPI/VCIs. This table is dynamic and is
updated on a call by call basis. ATM label converter 230 is
functional to change the VPI/VCIs in incoming ATM cells to new
VPI/VCIs based on the table in header mapper 210.
[0030] ATM interface 220 is functional to accept incoming cells
from connection 263 and then send the cells through label converter
230. ATM interface 240 is functional to accept converted cells from
ATM label converter 230 and transmit these cells on connection 264.
These ATM interfaces are also able to perform reciprocal processing
for ATM traffic flowing in the reverse direction.
[0031] Telecommunications signaling is used to set-up and tear down
connections for a call. Setting-up a connection would entail
creating a series of logically connected VPI/VCI communications
paths from end to end. The following operation of the invention is
described in terms of SS7, but those skilled in the art are aware
of other signaling systems that could also be used with the
invention. Some examples of these other signaling systems would be
C7 and UNI.
[0032] Typically, the network providing cells to gateway 200 does
not have knowledge of the actual destination for these cells beyond
gateway 200. This "first" network will also produce an Initial
Address Message (IAM) associated with the call. The IAM contains
information that can be used to route the cells for the call. The
IAM is transferred to CCM 270. CCM 270 will process the IAM
according to the requirements of the "second" network receiving
cells from gateway 200. CCM 270 will select a new VPI/VCI based on
the IAM.
[0033] In one embodiment, the system would operate as follows for a
call incoming over connection 263. Typically, the network providing
the call to gateway 200 will seize an available connection
(VPI/VCI) to gateway 200. This connection is represented by
connection 263. CCM 270 will receive the IAM produced in
association with the call over link 261. The routing label in the
IAM contains a Circuit Identification Code (CIC). The CIC
identifies the VPI/VCI in the incoming cells for the call. In other
words, the CIC in the IAM identifies the seized connection (in
connection 263) to gateway 200. CCM 270 will select the VPI/VCI for
routing the call over connection 264. CCM 270 then sends a control
message to control interface 250 through link 260. The control
message will instruct gateway 200 to modify the VPI/VCI of the
incoming cells so they contain the VPI/VCI selected by CCM 270.
Control interface 250 responds with an acknowledgment over link 260
to CCM 270. In the case of error conditions, the acknowledgment
will be negative acknowledgment. Header mapper 210 will receive the
instruction information from control interface 250 and will store
this information for the duration of the call. CCM 270 would also
generate another IAM for transfer over link 262 to the next node
requiring a call message.
[0034] Cells for the call will arrive at ATM label converter 230
from ATM interface 220 and connection 263. ATM label converter 230
will use the VPI/VCI of the incoming cells as the key to enter
header mapper table 210 to yield the new VPI/VCI. ATM label
converter 230 will modify the VPI/VCI in the cell headers to the
new VPI/VCI. The cells are then forwarded to ATM interface 240 for
transmission over connection 264.
[0035] At the end of the call, a release message (REL) is received
by CCM 270 over link 261. The REL will cause CCM 270 to begin call
tear down procedures. CCM 270 will send a control message to
control interface 250 over link 260. Control interface 250 will
send the information to header mapper 210 disassociating the
incoming and outgoing VPI/VCI for the call. This will cause gateway
200 to terminate the call connection. CCM 270 will then send an
appropriate REL over link 262 to the next node. Those skilled in
the art will appreciate that other procedures can also be used at
the end of the call. For example, the CCM may allow the VPI/VCI
assignment to remain for a specified duration.
[0036] Preferably, connection 264 would transfer these modified
cells to an ATM cross-connect system that has pre-provisioned
VPI/VCIs to potential network destinations. Because the VPI/VCI is
selected in real time by CCM 270 based on the signaling and the
routing configuration, gateway 200 is able to implement SVCs on a
call by call basis. It can be appreciated that by using the
requirements for the network accepting the cells, CCM 270 and
gateway 200 can implement SVCs for calls proceeding in both
directions. It is also important to note that this can be done
without the need for a complex ATM switch with signaling and call
processing capability.
[0037] FIG. 3 shows another version of the invention. In this
version, SS7 signaling is used, but other signaling could be used
in other versions. Shown are ATM system 300 and ATM system 350. ATM
system 300 is comprised of gateway 305, call/connection manager
(CCM) 310, Signal Transfer Point (STP) 315, ATM cross-connect 320,
and nodes 325, 330, 335, and 340. ATM system 350 is comprised of
gateway 355, CCM 360, STP 365, ATM cross-connect 370, and nodes
375, 380, 385, and 390.
[0038] For the sake of clarity, the connections and links are not
numbered. Virtual paths are shown (single lines) provisioned
through ATM cross-connect 320 between gateway 305 and nodes 325,
330, 335, and 340. Virtual paths are shown provisioned through ATM
cross-connect 370 between gateway 355 and nodes 375, 380, 385, and
390. Gateway 305 and gateway 355 are connected by a virtual path as
well. Signaling links are shown interconnecting the various
components (as discussed above, the link between the CCM and the
gateway could also be a conventional datalink or bus arrangement).
Note that cross-connects 320 and 370 do not require signaling. They
are provisioned and do not need signaling/switching capability on a
call-by-call basis.
[0039] Gateway 305 and 355 have been described above. They modify
the VPI/VCIs in ATM cells as instructed by control messages from
the CCMs. CCM 310 and 360 are described above and in detail below.
They process signaling and select VPI/VCIs on a call by call basis.
The selections are provided to the gateways. STPs 315 and 365 are
known in the art. They route signaling messages. ATM cross-connects
320 and 370 are known in the art. They route ATM cells based on a
pre-provisioned routing configuration and the VPI/VCI in the cells.
Nodes 325, 330, 335, 340, 375, 380, 385, and 390 are ATM devices.
Any device that transmits or receives ATM cells is contemplated by
the invention. Some examples are ATM switches, ATM cross-connects,
and ATM Customer Premises Equipment (CPE). Some of these nodes may
use signaling and some may not need signaling.
[0040] In operation, this version of the invention works as follows
for a call from node 325 to node 385. Node 325 would recognize that
the call did not terminate within network 300 and would seize a
connection to gateway 355. This connection would be provisioned
through cross-connect 320 and represented by the VPI/VCI in the
cell headers. Gateway 305 is inactive on this call and could even
be omitted. It is shown to illustrate the Gateway function could be
implemented for calls passing in the other direction. Node 325
would also transfer an IAM to CCM 360 identifying the seized
VPI/VCI. The IAM would be routed by STP 315 and STP 365 to CCM 360.
It is important to note that ATM system 300 does not know the
routing configuration of ATM system 350.
[0041] CCM 360 will process the IAM from Node 325 to select a
VPI/VCI to node 385. Gateway 355 has a provisioned virtual path to
node 385 through cross-connect 370. CCM 355 would select an
available VCI within that VPI. CCM 360 would identify both the
VPI/VCI from gateway 305 and the VPI/VCI to node 385 in a control
message to gateway 355. Gateway 355 would modify the old VPI/VCI to
the new VPI/VCI selected by CCM 360 and transfer the modified cells
to cross-connect 370. Based on its pre-provisioned routing
configuration and the VPI/VCI selected by CCM 360, cross-connect
370 would transfer these cells to node 385. If necessary, CCM 360
would transfer an IAM to node 385 through STP 365.
[0042] It should be appreciated that the above procedure could be
repeated for multiple calls between different nodes. This includes
calls from network 350 to network 300. The CCM, the gateway, and
the cross-connect work together to provide SVCs on a call-by-call
basis. This accomplished without the cost or complexities of an ATM
switch.
The Call/Connection Manager (CCM)
[0043] FIGS. 4-13 refer to a preferred embodiment of the signaling
processor, also known as the CCM, but any processor which supports
the requirements stated for the invention would suffice. FIG. 4
depicts a signaling processor suitable for the invention. Signaling
processor 400 would typically be separate from the gateway, but
those skilled in the art appreciate that they could be housed
together and coupled in a bus arrangement instead of being coupled
by a data or signaling link. Signaling processor 400 may support a
single gateway or support multiple gateways.
[0044] Signaling processor 400 includes Message Transfer Part (MTP)
410. MTP 410 can be comprised of signaling point software that is
known in the art. MTP 410 includes various levels known as MTP 1,
MTP 2, and MTP 3. MTP 1 defines the physical and electrical
requirements for a signaling link. MTP 2 sits on top of MTP 1 and
maintains reliable transport over a signaling link by monitoring
status and performing error checks. Together, MTP 1-2 provide
reliable transport over an individual link. A device would need MTP
1-2 functionality for each link it uses. MTP 3 sits on top of MTP 2
and provides a routing and management function for the signaling
system at large. MTP 3 directs messages to the proper signaling
link (actually to the MTP 2 for that link). MTP 3 directs messages
to applications using MTP 410 for access to the signaling system.
MTP 3 also has a management function which monitors the status of
the signaling system and can take appropriate measures to restore
service through the system. MTP levels 1-3 correspond to layers 1-3
of the open systems interconnection basic reference model (OSIBRF).
MTP 410 could also include Signaling Connection Control Part (SCCP)
functions, as well as, TCAP, and ISUP functional interfaces. In
addition, MTP 410 may be equipped with ISUP timers that generate
release messages or re-transmit messages where appropriate. If
B-ISUP signaling is being used, MTP 410 could also be equipped with
B-ISUP capability. All of these elements are known in the art.
[0045] Also shown for signaling processor 400 are platform handler
420, bearer control 430, message handler 440, and record handler
450. MTP 410 could be connected to platform handler 420 by an
ethernet interface supporting TCP/IP which transfers signaling
messages from MTP 410 to platform handler 420. Those skilled in the
art will recognize other interfaces and protocols which could
support these functions in accord with the invention.
[0046] Platform handler 420 is a system which accepts ISUP messages
from MTP 410 and routes them to message handler 440. Message
handler 440 is a system which exchanges signaling with platform
handler 420 and controls the connection and switching requirements
for the calls. Bearer control 430 handles bearer capabilities for
the call. Record Handler 450 generates call records for back-office
systems.
[0047] In operation, ISUP messages are routed by MTP 410 to
platform handler 420. Platform handler 420 would route the ISUP
messages to message handler 440. Message handler 440 would process
the ISUP information. This might include validation, screening, and
retrieving additional data for call processing. Bearer control 430
would implement the bearer capabilities required, such as digital
signal processing (DSP), through control messages to the
appropriate network elements. Message handler 440 would complete
call processing. Message handler 440 would generate the appropriate
messages to implement the call and pass the messages to platform
handler 420 for subsequent transmission to the designated network
elements. Message handler 440 would also receive ISUP messages from
MTP 410 at the completion of the call. Message handler 440 would
process these messages and generate subsequent messages to tear
down the call. Record handler 450 would obtain call information
from message handler 440 and use this information to generate call
records. The call records could be used for billing purposes.
[0048] Functional entities are well known in the art. Message
handler 440 includes at least the call control function (CCF) and
the service switching function (SSF). The CCF establishes and
releases call connections, and the SSF recognizes triggers during
call processing by the CCF and provides an interface between the
CCF and the service control function (SCF). The SCF identifies
services and obtains data for the service, and is preferably housed
in a remote database, such as an SCP. (As such, the SCF is not
shown on FIG. 4.) Message handler 440 is able to control
connections, recognize triggers, and access the SCF in a remote
database.
[0049] Signaling processor 400 is comprised of hardware and
software. Those skilled in the art are aware of various hardware
components which can support the requirements of the invention. One
example of a such hardware is the FT-Sparc provided by Integrated
Micro Products PLC. The FT-sparc could use the Solaris operating
system also provided by Integrated Micro Products PLC. MTP 410
could be constructed using commercially available SS7 software
interface tools. An example of such tools would be SS7 interface
software provided by either Trillium, Inc or by Dale, Gesek,
McWilliams, and Sheridan, Inc. Any data storage requirements could
be met with conventional database software systems.
[0050] Software for platform handler 420, bearer control 430,
message handler 440, and record handler 450 could be produced in
the following manner. The Intelligent Network Conceptual Model
(INCM) of the ITU-T Q.1200 series could be mapped to Specification
Design Language (SDL) of ITU-T Z.200 and Message Sequence Charts
(MSC) of ITU-T Z.120. Various detection points and points-in-call
in the INCM can be skipped to optimize call processing. The SDL
could then be compiled into C or C++ and loaded onto the FT-sparc.
The software is primarily comprised of several static processes,
instantiated processes (from static processes), and communication
channels between the processes. Preferably, the software processes
would be partitioned into several operating system tasks. Further
requirements for the software design will become apparent in the
following discussion.
The Platform Handler
[0051] Platform handler 420 is preferred, but is not required as
its functions could be handled by MTP 410 and/or message handler
440. Platform handler 420 has messaging interfaces that exchange,
buffer, dis-assemble, and re-assemble messages for MTP 410, bearer
control 430, message handler 440, and record handler 450. Platform
handler 420 could exchange these messages over an ethernet--TCP/IP
interface, but any technique for transfer of messages is
contemplated by the invention. Platform handler 420 could also
check the messages for basic flaws. Should more than one message
handler be connected to platform handler 420, ISUP messages could
be allocated to the message handlers based on the SLS of the
particular ISUP message. Platform handler 420 also accepts routing
instructions from message handler 440 for routing certain ISUP
messages to particular select call model processes of message
handler 440.
[0052] Platform handler 420 is also responsible for managing and
monitoring CCM activities. Among these are CCM start-up and
shut-down, log-in and log-off of various CCM modules, handling
administrative messages (i.e. error, warning, status, etc.) from
the CCM modules, and handling messages from network operations such
as queries, configuration instructions, and data updates. The
connections to the various CCM modules are shown. The connection to
network operations is the man machine interface which allows the
CCM to be controlled and monitored by either a remote or a local
operator. Platform handler 420 has a process which retrieves
configuration data from internal tables to initialize and configure
the CCM. The CCM modules also have internal tables which are used
in conjunction with this procedure.
The Message Handler.
[0053] FIG. 5 depicts a version of the message handler. External
connections have been omitted for the sake of clarity. Message
handler 500 is shown and includes ISUP 510, call manager 520,
feature manager 530, switching manager 540, and SCF access manager
550. The primary function of message handler 500 is to process ISUP
messages for calls, generate subsequent messages, and invoke
services. As a result of its processing, message handler 500 is
able to assign incoming access connections (CICs in SS7) to
VPI/VCIs and instruct the gateway to provide SVPs and SVCs through
an ATM cross-connect system.
[0054] ISUP 510 receives generic ISUP messages from the platform
handler and converts them into specially formatted ISUP messages
using receive 512. ISUP 510 reverses this process in transmit 514
for messages sent to the platform handler. Receive 512 forwards
formatted messages to call manager 520. ISUP 510 also exchanges
local management message with the platform handler.
[0055] Call manager 520 could include the functionality specified
in the Intelligent Network Call Model (INCM) of ITU-T Q.1214 which
encompasses the main functionality of the CCF. Call center 522
receives IAM messages and creates an originating call model process
for each IAM. Each originating process is parameterized with data
from its particular IAM. Additional origination processes can be
created based on the IAM if it is a multi-party call. All of these
originating processes are represented by originating processes
524.
[0056] An originating process will typically create a detection
point process. All of the detection point processes created are
represented by detection point processes 526. Each originating
process will also set-up a call control block containing data for
the call. Each origination process will execute through a point-in
call to a detection point. When detection points are encountered,
and the originating process has not been programmed to skip them, a
signal representing the detection point is forwarded to the
corresponding detection point process. As stated above, call
processing can be streamlined by skipping selected detection points
and points-in-call. When an originating process sends a detection
point signal to the corresponding detection point process,
processing is suspended at the originating process until a response
is received from the detection point process.
[0057] Detection point processes 526 provides a portion of the SSF
and acts as a buffer between the call processes and feature manager
530. A detection point process analyzes the detection point signal
from the origination process to determine if is should be acted on
or if it can be ignored. If the processing results in a service
request or notification, a corresponding signal is sent to feature
manager 530. Detection point responses from feature manager 530 are
forwarded back to the appropriate call process. Once call set-up
has been authorized for the originating process, a detection point
process will also send a signal to call center 522 to create a
terminating process.
[0058] These terminating processes are represented by terminating
processes 528. A terminating process creates and interacts with
detection point processes 526 much like an originating process. A
terminating process also creates a terminating call control block.
ISUP information is transferred from the originating process for a
call to the terminating process for the call. The platform handler
is instructed of the originating and terminating processes so that
subsequent ISUP messages related to that call can be transferred
directly to the appropriate processes by the platform handler. Both
originating and terminating processes have a local database. For
example, a termination process might access local data to translate
the NPA-NXX of a dialed number into the VPI to a destination
gateway.
[0059] The originating processes and terminating processes also
exchange messages with bearer control. Typically, these messages
relate to DSP and gateway control. For calls that pass through two
gateways (an originating gateway into the ATM network and a
terminating gateway out of the ATM network), both an origination
and termination process is required for each gateway--a total of
four call processes. The termination process for the origination
gateway will handle mapping the incoming VPI/VCI to the VPI/VCI
through the ATM network. The termination process for the
terminating gateway will map the VPI/VCI through the ATM network to
an outgoing VPI/VCI. If only one gateway is used on the call (in
and out of the network at the same gateway), only a single
origination process and a single termination process is
required.
[0060] The originating processes and terminating processes also
exchange messages with the record handler. Typically, these
messages relate to billing and operational measurements. Upon call
tear down, the record handler receives the originating and
terminating call control blocks for billing purposes. These call
control blocks typically would identify the following: the call
control block ID, the originating/terminating process ID, the
message handler, the originating LEC, the LEC trunk circuit (CIC),
the ATM virtual circuit, the ATM virtual path, the caller's number,
the dialed number, the translated dialed number, the originating
line information, the ANI service class, the selected route, the
number of the selected route, the SLS, the OPC, the DPC, the
service indicator (SIO), reason of release, call status, and
pointers to adjacent call control blocks. In addition, the call
control block would also contain the various times that signaling
messages are received, such the address complete message (ACM), the
answer message (ANM), the suspend message (SUS), the resume message
(RES), and the release message (REL). Those skilled in the art
would be aware of other pertinent data to include.
[0061] Call manager 520 communicates with feature manager 530.
Feature manager 530 handles interaction of services for the call.
Examples of services would be 800 calls, PCS calls, and VPN calls,
but there are many others. Feature manager 530 is comprised of
feature center 532 and feature processes 534. Feature center 532
receives the detection point messages from the detection point
processes 526. Feature center 532 then creates a feature process
for each call. These processes are represented by feature processes
534. The feature process will determine if additional data is
needed for the detection point. If so, a signal is sent to
switching manager 540. Responses from switching manager 540 are
sent to the appropriate detection point process by the feature
process for the call.
[0062] In this embodiment, the feature process sends all such
service signals to switching manager 540. In other embodiments,
services may be segregated into "IN" and "non-IN" services, the
feature process would then have to select between an "IN" switching
manager or a "non-IN" switching manager when sending service
signals to switching manager 540.
[0063] Switching manager 540 is comprised of switching center 542
and switching processes 544. Switching manager 540 creates a
switching process for each service required on the call. These
switching processes are represented by switching processes 544. A
switching process will communicate directly with the associated
feature process for the call. The switching process will also
interface with the SCF. As stated above, the SCF provides the
service processing for the call and is preferably located at a
remote database. A typical example of accessing SCF would be to
send a TCAP query to a Service Control Point (SCP) for an "800"
number translation. In order to access the SCF, the switching
process will use SCF access manager 550. SCF access manager 550 is
comprised of encoder 552 and decoder 554. Encoder 552 converts
signals from switching processes 544 into the proper format for SCF
access. Decoder 554 converts messages from the SCF back into the
format for switching processes 544. SCF access manager 550 would
typically access the SCF over standard communications links. One
example would be an SS7 link using the TCAP/INAP/ASN.1 protocol
specified by the ITU. If SS7 is used, SCF access manager 550 could
forward its TCAP messages to the MTP function (MTP 410 of FIG. 4)
for subsequent transfer to an STP and SCP.
[0064] From the above discussion, it should be clear that message
handler 500 is comprised of static processes identified as
"centers" that create specific processes for each call. Once
created, these specific call processes communicate directly with
one another to accomplish call processing.
Bearer Control and the Record Handler
[0065] As stated bearer control will handle DSP requirements and
gateway control. An example of DSP requirement would be to adjust
the decibel level. An example of a gateway control would be a
VPI/VCI assignment. After a release message on a call, the
originating and terminating processes will forward the information
in the call control block to record handler 450. Record handler 450
will use the call control block to create a billing record. The
call control block would contain information from the ISUP messages
for the call and from CCM processing. From the address complete
message (ACM), the call control block would include the routing
label, CIC, message type, and cause indicators. From the answer
message (ANM), the call control block would include the routing
label, CIC, message type, and backward call indicators. From the
initial address message (IAM), the call control block would include
the routing label, CIC, message type, forward call indicators, user
service information, called party number, calling party number,
carrier identification, carrier selection information, charge
number, generic address, origination line information, original
called number, and redirecting number. From the release message
(REL), the call control block would include the routing label, CIC,
message type, and cause indicators. From the suspend message (SUS)
or the pass along message (PAM), the call control block would
include the routing label, CIC, and message type. Those skilled in
the art are familiar with other pertinent information for a billing
record and appreciate that some of this information could be
deleted. The billing record will be forwarded by record handler 450
to a billing system over a billing interface. An example of such an
interface is an ethernet--FTAM protocol.
Call Processing
[0066] SS7 messaging is well known in the art. SS7 ISUP messages
contain numerous fields of information. Each message will have a
routing label containing a destination point code (DPC), an
origination point code (OPC), and a signaling link selection (SLS)
which are used primarily for routing the message. Each message
contains a circuit identification code (CIC) which identifies the
circuit to which the message relates. Each message contains the
message type which is used to recognize the message. ISUP messages
also contain mandatory parts filled with fixed length data and
variable length data, in addition to a part available for optional
data. These parts vary from message type to message type depending
on the information needed.
[0067] The initial address message (IAM) initiates the call and
contains call set-up information, such as the dialed number. IAMs
are transferred in the calling direction to set up the call. During
this process, TCAP messages may be sent to access remote data and
processing. When the IAMs have reached the final network element,
an address complete message (ACM) is sent in the backward direction
to indicate that the required information is available and the
called party can be alerted. If the called party answers, an answer
message (ANM) is sent in the backward direction indicating that the
call/connection will be used. If the calling party hangs up, a
release message (REL) is sent to indicate the connection is not
being used and can be torn down. If the called party hangs up, a
suspend message (SUS) is sent and if the called party reconnects, a
resume (RES) message keeps the line open, but if their is no
re-connection, a release message (REL) is sent. When the
connections are free, release complete messages (RLC) are sent to
indicate that the connection can be re-used for another call. Those
skilled in the art are aware of other ISUP messages, however, these
are the primary ones to be considered.
[0068] In the preferred embodiment, call processing deviates from
the basic call model recommended by the ITU, although strict
adherence to the model could be achieved in other embodiments.
FIGS. 6-13 depict message sequence charts for the call processing
in one embodiment. Message sequence charts are known in the art,
and are a recognized format to depict call processing. At the top
of the chart, the basic elements of the CCM are shown--the platform
handler, the message handler, the bearer control, and the record
handler. The blocks below the message handler indicate the
processes for the message handler. Further specification at the
process level for the platform handler, the bearer control, and the
record handler is not required for this discussion. The charts are
read down in a chronological sequence. Blocks indicate tasks
performed by the process named above. Arrows indicate messages
exchanged between the processes or the creation of a new process by
an existing process.
[0069] The sequence starts on FIG. 6 with an ISUP message at the
platform handler. The platform handler forwards the message to the
ISUP receive process of the message handler. If the ISUP message is
an IAM, the ISUP receive process forwards the IAM to the call
center. The call center had been in the "origination null"
point-in-call, but the IAM causes the call center to create an
originating call process parameterized with contents of the IAM.
The originating process then executes through the "authorize
origination attempt" point-in-call. This typically entails ANI
validation in a look-up table, but prior to the look-up, call
information is checked to determine if ANI validation is required.
For particular types of calls, i.e. "800" calls, origination is
authorized without ANI validation.
[0070] Once origination has been authorized, the originating
process creates a detection point process and transmits a signal to
the detection point process that origination has been authorized.
The detection point process returns a message instructing the
origination process to execute through the "analyze information"
point-in-call, although a detection point could be programmed at
this point if desired. Continuing on to FIG. 7, "Analyze
information" typically entails verifying that the dialed number is
legitimate and checking call information for any applicable
services. A few examples of a services are "800" and PCS. In this
example, no services are required for the call--the call is a
typical POTS call. Once the analysis has been accomplished, the
originating process sends a "analyzed information" message to the
detection point process. Typically, the detection point process
returns a "resume" message to the originating process, but
detection points could be programmed here if desired.
[0071] The resume message causes the origination process to execute
through the "routing and alerting" point-in-call. This typically
entails translating the dialed number to select a destination
address. For example, the NPA-NXX of the dialed number could be
used in a look-up table to yield the address of the terminating
gateway and the device that should receive the call from the
gateway. The origination process will also send a message to the
call center to create an terminating call process. The terminating
call process is provided with the identity of the originating
process. The terminating process also creates a detection point
process to handle the detection points it encounters. For purposes
of clarity, this is indicated along the same line as the
originating process detection point, although it should be
understood that each process communicates with its corresponding
detection point.
[0072] Continuing on to FIG. 8, the terminating process executes
through the "authorize termination attempt" point-in-call. This
typically entails verifying that an ATM connection to another
gateway can be attempted. For example, the CCM and the gateway at
the terminating end must be operational to handle the call. Once
termination is authorized, an authorized message is sent to the
detection point process, which returns a resume message to the
termination manager (unless a detection point is programmed into
the detection point process.)
[0073] The terminating process will then execute through the
"select facility and present call" point-in-call. This typically
entails selecting the actual VPI/VCI and outbound connection for
the call. The destination has already been specified during the
"routing" point-in-call, so the VPI/VCI and point codes can be
looked-up accordingly. The terminating process will then send a
message to bearer control requesting gateway control. Bearer
control would then create a message for the originating gateway
identifying the connections and devices relevant to the call.
Bearer control would respond that gateway control was handled.
Continuing on to FIG. 9, the terminating process would then
construct an IAM for transmission to the downstream CCM at the
terminating gateway. As discussed above, this message could be
coded such that the downstream CCM could skip detailed call
processing. The IAM would be provided to the ISUP sender and a
formatted IAM would be provided to the platform handler for
subsequent transmission to the downstream CCM.
[0074] On a typical call, the next message that would be received
by the CCM that is related to the call would be an Address Complete
Message (ACM) signifying that the terminating end of the call had
the information required to complete the call. The external device
would send an ACM back to the terminating CCM which would pass on
an ACM to the originating CCM. These procedures at the terminating
CCM are not depicted in the message sequence chart. The message
sequence chart continues with the ACM arriving at the originating
CCM.
[0075] The ISUP receive process would forward the ACM to the
terminating process. The terminating process would execute through
the "alerting" point-in-call and would send ACM information to the
originating process, which would also execute through the
"alerting" point-in-call. Alerting entails alerting the users that
a connection is available--i.e. ringing a telephone. Typically, no
specific activity is required for "alerting", but detection points
could be inserted into the process if desired. The originating
process would forward an ACM to the ISUP sender which would provide
a formatted ACM to the platform handler for subsequent transmission
to devices at the origination side of the call.
[0076] On the typical call, an Answer Message (ANM) will be
transferred from the terminating side of the call to the
origination side of the call when the called party answers the
phone. The ANM is received by the platform handler and forwarded to
the ISUP receive process which forwards its version to the
terminating process. Continuing on to FIG. 10, the terminating
process executes though the "active" point-in-call and sends ANM
information to the detection point process. Typically, the
detection point process will return a resume message, although
detection points could be included here if desired. The terminating
process also sends a gateway control message to bearer control to
facilitate cut-through on the call at the gateway. A acknowledgment
response is sent back to the terminating process from bearer
control. The terminating process also sends ANM information to the
originating manager, which also executes through the "active"
point-in-call. The originating process also sends an answer message
to the detection point process and a partial call control block to
the record handler. Typically, the detection point process will
send a resume message back to the origination process. The
originating process would forward an ANM to the ISUP sender which
would provide a formatted ANM to the platform handler for
subsequent transmission to devices at the origination side of the
call. At this point, the call is in progress.
[0077] The message sequence continues with the receipt of a release
message (REL) after the caller or called party hang up. As stated
above, if the called party hangs up, a suspend message (SUS) is
sent before the call is released, but if the caller hangs up, only
an REL is sent. For clarity, the chart picks up with an REL
arriving from the terminating side of the call. The REL is received
by the platform handler and transferred to the ISUP receive
process, which provides its version of the message to the
terminating process. (Had the REL been from the originating side,
it would have been provided to the originating process.) The
terminating process executes through the "disconnect"
point-in-call. Continuing on FIG. 11, the terminating process sends
REL information to the originating process. The originating process
would forward an REL to the ISUP sender which would provide a
formatted REL to the platform handler for subsequent transmission
to devices at the origination side of the call. In response to the
REL, the terminating process will forward a Release Complete
Message (RLC) to the ISUP sender which would provide a formatted
RLC to the platform handler for subsequent transmission to the
device that sent the REL. The RLC acknowledges the REL and
signifies that the call connections may be torn down and re-used.
The terminating process also sends a gateway control message to
bearer control to cause the relevant VPI/VCI to be torn down, and
receives an acknowledgment response from bearer control.
[0078] The next message will typically be an RLC in response to the
REL sent to the originating side of the call. The RLC is received
by the platform handler and forwarded to the ISUP receive process.
ISUP receive provides its version of the message to the originating
process. This causes the originating process to forward its final
call control block to the record handler. The originating process
also provides RLC information to the terminating process. This
causes the terminating process to send its final call control block
to the record handler. The record handler responds to each process
with an acknowledgment response. Continuing on to FIG. 12, tear
down messages are sent by the originating process and the
terminating process to their respective detection point processes.
Typically, no detection points will be programmed and the
originating process, the terminating process, and the detection
point processes will terminate and be cleared from the CCM.
[0079] FIG. 13 also depicts a modified excerpt from the message
sequence charts above. The modification is for a call that requires
services. Services might include N00 or VPN calls, but many other
services are known. In this embodiment, an SCP is accessed to
provide information to implement the service. As shown, call
processing picks up where the detection point process for either
the originating process or the terminating process analyzes a
detection point and determines that a service is required.
Typically, this is done by examining the dialed number and the
caller's number. Those skilled in the art are aware of how services
can be determined from call information.
[0080] If it is determined that a service should be applied to the
call, the detection point process sends detection point message to
the feature center that causes the feature center to create an
feature process. The feature process will be parameterized with
call information and will send a detection point message to the
switching center. In some embodiments, the feature process will
choose between "IN" services and "non-IN" services and send the
detection point message to the corresponding switching center. Upon
receiving the message, the switching center creates a service
process for each service to be applied to call. The service process
formulates a request for service information and forwards it to the
encoder of the SCF access manager. The encoder produces a TCAP
message and transmits it over the appropriate link to a remote SCF.
(possibly through the platform handler and/or the MTP interface).
The remote SCF will return a response to the decoder. The response
is formatted for the service process and sent to it. The service
process takes the response and formulates an analyze information
message that is transferred back through the feature process to the
detection point process. The detection point process transfers the
analyze information message to the applicable originating or
terminating process. Subsequent call processing remains the same as
discussed above. At call tear down, the feature process and the
switching process are cleared from the CCM.
[0081] An example of the above scenario would be for an "800" call.
The CCM would recognize that the "800" in the called number
required service application. As a result, it would generate and
transmit TCAP query to an SCP requesting an "800" translation. The
SCP would process the query and translate the "800" number into a
POTS number. The SCP would return the POTS number to the requesting
CCM. The CCM would then process the POTS number as it would for a
standard POTS call.
[0082] In some embodiments, the CCM processes SS7 signaling
messages to accomplish the following functions: validation,
routing, and billing. SS7 messages are well known in the art. The
following sections discuss SS7 processing, but those skilled in the
art will recognize variations that are also contemplated by the
invention. In SS7, the routing labels of the messages are used to
correlate messages to calls. Contemporaneous messages with the same
OPC, DPC, and CIC relate to the same call.
[0083] To validate a call, the routing label of messages should be
checked. The Service Indicator should be checked to distinguish
between an incoming message from outside of the network or a
message from a network CCM. The Destination Point Code is screened
to ensure the destination of the SS7 message is actually destined
for the CCM. The Originating Point Code is screened to ensure the
originating point code is allowed in the CCM. The Message Type is
screened to ensure that the type of message is allowed in the CCM
and that there are no protocol violations associated with the
message.
[0084] Both the Circuit Reservation Message (CRM) and the IAM
should have the Satellite Indicator screened to ensure that the
limit on the number of Satellites in a circuit has not been
exceeded. This will be on a trunk group by trunk group basis. The
REL automatic congestion level will be screened to see if
congestion arises. The CCM should then control calls to the
associated network elements until the congestion abates. For
non-call associated messages, the circuit group supervision message
type indicator will be screened to compare the state of the
circuits with the instructions incoming in the messages.
[0085] The IAM will receive additional treatment for validation.
Information Transfer Capability will be screened to ensure that the
connection for the call is capable of handling the transfer rate
requested. The Coding Standard will be screened to ensure that the
standard is coded 00. All others will be rejected. Transfer Mode
will be screened to ensure that the mode is coded 00 for 64
Kbit/second calls. User Layer Protocol ID and the Rate field will
be screened to ensure that there is no rate adaptation required for
the call. The Network ID Plans and Digits, will be screened to
ensure that the carrier identification field and the transit
network carrier identification field is in the correct format. The
Circuit Code will be screened to allow callers with the correct
means of dialing to access the network.
[0086] The CCM will check the Hop Counter in the IAM to determine
if it has reached its limit as set by this field (range 10 to 20
with a default of 20). If it has not, the CCM will increment the
parameter. If it has reached the determined count, the CCM will
send a release message back with a cause of "exchange routing
error" to tell the preceding switch that the IAM has reached its
limit in hops. If this field is left blank, the CCM will not
increment the counter parameter and pass the IAM unchanged.
[0087] The IAM Called Party Number field should be handled as
follows for validation. Nature of Address will tell the CCM what
type of number was dialed for the called number. The screening of
this field will be for a non-NPA number. If that occurs, the CCM
will need to add the NPA from the Trunk Group to the call control
block. Numbering Plan will be screened to check what type of plan
the incoming called party number uses. The only allowable plans are
Unknown and ISDN numbering plans. All others should be disallowed.
Digits Field will be screened for the number of digits using the
Nature of Number, Odd/Even, and Digits Fields to determine the
correct number of digits.
[0088] The IAM Calling Party Number and Charge Number fields should
be handled as follows for validation. Nature of Address will be
screened to ensure that the calling party's number is in the proper
format. Presentation Allowed/Restricted will be screened to check
for N00 calling. Numbering Plan will be checked to ensure that the
numbering plan is set at either unknown or ISDN numbering plan.
Digits Field will be checked to ensure that there is enough digits
for an ANI that can be billed. These digits will be validated in an
ANI table for call authorization.
[0089] Routing is primarily accomplished by processing the IAM.
Called Party Number--Nature of Address, Digits--This will tell the
CCM what type of call this is. It will differentiate 0+, test
calls, and International numbers from normal 1+ calls. The Calling
Party's Category tells the CCM that the call is a test call with
different routing than a normal call. The Carrier Identification
Plan will be used to determine if the CCM receives the Carrier
Identification Code of another carrier, since the CCM may wish to
route the call based on the subscribers choice of carriers. The IAM
Carrier Selection Information is used to route the call based on
whether the subscriber was presubscribed or dialed the carrier
access number. The IAM Originating Line Information will enable the
CCM to route based on what type of originating line is being used
for this call. An example is if a payphone makes a 1+call, the CCM
will be able to route the call directly to an operator for billing
arrangements. The IAM Transit Network Selection fields will
indicate the Carrier Identification Code of the International
Carrier that is requested by the subscriber, so the CCM can route
the international call to the correct switch. The Circuit Code will
tell the CCM how the code was dialed. If the subscriber dialed an
access code for a different international carrier, the CCM could
route the call to an operator center for processing.
[0090] The IAM Called Party Number fields are handled as follows
for routing. Nature of Address Indicator tells what type of call is
being requested. This will include 0+ and 0- calls, international
calls (operator and non operator calls), cut through, and 950 types
of calls. With this information, the CCM can route the call
directly to the international gateway or operator center without
looking at the rest of the message. For normal 1+ calls, the
Odd/Even field will be used with the digits fields to determine the
number of digits. Numbering Plan field will be used to route calls
differently if it has a "Private Numbering Plan" value in the
field. Digits Field will be the digits that will be used to route
the call through the network using table look-ups. Typically, the
digits field houses the dialed number.
[0091] Billing will be based on the Call Control Blocks (CCBs)
created by the call processes. A portion of these records are
transferred from messages received by the CCM. The CCBs are
discussed above. When the Calling Party Number is present in the
IAM and there is no Charge Number present, the Calling Party Number
is used to bill the call. If the Charge Number is present in the
same message, then the Charge Number will be used for billing
instead of the Calling Party Number. Various messages need to be
tracked to measure the duration of the call. These include the IAM,
ACM, ANM, SUS, REL, and RLC. The causes associated with these
messages should also be considered.
[0092] The invention allows switching over an ATM fabric on a call
by call basis. This allows efficient high capacity virtual
connections to be exploited. Advantageously, the invention does not
require signaling capability in an ATM switch. The invention does
not require call processing capability in an ATM switch. This
enables networks to implement ATM switching without these
sophisticated ATM switches that support high volumes of calls. It
also avoids the cost of these switches. Relying on ATM
cross-connects is advantageous because ATM cross-connects are
farther advanced than ATM switches, and the cross-connects require
less administrative support.
[0093] Those skilled in the art will appreciate variations of the
above described embodiment. In some embodiments, other signaling,
such as C7 or UNI signaling could be used instead of SS7. Other
embodiments might make use of network management techniques to
control gateway 200. An example would be the use of a
Telecommunications Management Network (TMN) to control the gateway
in situations where slowly changing VPI/VCI mappings are needed.
Those skilled in the art will also appreciate that a gateway could
be implemented within a single network at points where dynamic
VPI/VCI conversion is desirable. Gateways between multiple
successive networks could also be employed. In addition to these
embodiments, other variations will be appreciated by those skilled
in the art. As such, the scope of the invention is not limited to
the specified embodiments, but is only restricted to the following
claims.
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