U.S. patent number RE36,354 [Application Number 08/283,282] was granted by the patent office on 1999-10-26 for key telephone system with virtual private lines.
This patent grant is currently assigned to IPC Information Systems, Inc.. Invention is credited to John M. Cotton, Neil C. Olsen.
United States Patent |
RE36,354 |
Cotton , et al. |
October 26, 1999 |
Key telephone system with virtual private lines
Abstract
A virtual private line key telephone system is provided. The
system includes a console including a plurality of line keys each
associated with a party that can be reached via a switched trunk
line. A look-up table means associates the line keys with the
telephone numbers of the associated parties. A communication path
is established from the console to one of the trunk lines. Signals
are sent to the central office via the selected trunk line
corresponding to the telephone number in the look-up table means
associated with a line key that is actuated to place a calls. The
telephone number of incoming calls are determined and compared with
telephone numbers in the look-up table. Thereafter the line keys
which are associated with the incoming calls are determined. The
incoming call is coupled to the console when a line key associated
with the incoming caller is actuated.
Inventors: |
Cotton; John M. (East Norwalk,
CT), Olsen; Neil C. (Milford, CT) |
Assignee: |
IPC Information Systems, Inc.
(New York, NY)
|
Family
ID: |
25077094 |
Appl.
No.: |
08/283,282 |
Filed: |
July 29, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
766648 |
Sep 26, 1991 |
05214691 |
May 25, 1993 |
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Current U.S.
Class: |
379/157;
379/142.17; 379/165; 379/171; 379/258; 379/268 |
Current CPC
Class: |
H04Q
11/0471 (20130101); H04Q 11/0428 (20130101); H04M
9/005 (20130101); H04M 1/57 (20130101); H04M
7/009 (20130101) |
Current International
Class: |
H04Q
11/04 (20060101); H04M 9/00 (20060101); H04M
001/26 () |
Field of
Search: |
;379/156,157,158,165,171,168,167,268,142,127,201 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0388648 |
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Feb 1990 |
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EP |
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2016865 |
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Sep 1979 |
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GB |
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WO8804869 |
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Jun 1988 |
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WO |
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WO8807297 |
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Sep 1988 |
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WO |
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WO8911764 |
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Nov 1989 |
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WO |
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WO9004316 |
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Apr 1990 |
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WO |
|
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Capabilities for the Belgian Broadband Experiment", Proceedings of
the Int'l Switching Symposium, Stockhom. SE, May 28-Jun. 1, 1990,
vol. V. pp. 111-118/. .
Henrion, M.A., et al. "Switching Network Architecture for ATM Based
Broadband Communications", Proceedings of the Int'l Switching
Symposium, Stockholm, SE, May 28-Jun. 1, 1990, vol. V., pp. 1-8.
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Boettle, D. and Henrion, M.A. "Alcatel ATM Switch Fabric and Its
Properties", 1225 Electrical Communication, 64 (1990) No. 2/3,
Ramford, Essex, GB, pp. 156-165. .
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2-3, 1981, Harlow, pp. 148-160..
|
Primary Examiner: Kuntz; Curtis
Assistant Examiner: Loomis; Paul
Attorney, Agent or Firm: Morgan & Finnegan
Claims
We claim:
1. A virtual private line key telephone system comprising:
a console including a plurality of line keys each associated with a
party that can be reached via a switched trunk line;
a look-up table means associating said line keys with the telephone
numbers of the associated parties;
means for establishing a communication path from said console to
one of said trunk lines and sending signals to the central office
via said selected trunk line corresponding to the telephone number
in said look-up table means associated with a line key that is
actuated to place a call;
means for determining the telephone number of incoming calls and
comparing said incoming call telephone number with telephone
numbers in said look-up table means to determine which line keys
are associated with the incoming call; and
means coupling the incoming call to the console when a line key
associated with the incoming caller is actuated.
2. The telephone system according to claim 1 wherein each of said
line keys includes a status indication which emulates private line
status indications.
3. The telephone system according to claim 1 wherein each of said
line keys includes a status indication where the status of a call
to a party is indicated at a fixed location associated with a
particular line key regardless of which trunk line is used for
.[.he.]. .Iadd.the .Iaddend.call.
4. The telephone system according to claim 1 wherein, said line
keys are located at a plurality of consoles,
said trunk lines are each associated with a line card capable of
detecting line status, and said look-up table means includes
a look-up tale at said console for associating line keys to virtual
logic address codes, and
a look-up table at said line card for associating virtual logic
address codes with said numbers of associated parties.
5. The telephone system according to claim 4 wherein the status of
the calls to associated parties is displayed at said console for
said line keys as though the .[.lien.]. .Iadd.line .Iaddend.key
were associated with a private line.
6. A virtual private line key telephone system comprising:
at least one console including a plurality of assignable line
keys;
a line key assignment look-up table for said console for
associating specific line keys to parties that can be reached via a
switched trunk line and a virtual logic address code;
at least one .[.lie.]. .Iadd.line .Iaddend.card for a switched
trunk line which can connect to multiple parties via a central
office switch and which provides calling party identification (cpi)
on incoming call;
a cpi look-up table for associating calling party identification
telephone numbers with virtual logic address codes;
means for placing an outgoing call on said switched .[.lien.].
.Iadd.line .Iaddend.by actuating a line key, looking up the virtual
logic address code associated with the line key and party, and
looking up the calling party identification telephone number
corresponding to the virtual logic address code and automatically
placing a call to said telephone number; and
.[.mean.]. .Iadd.means .Iaddend.for receiving incoming calls on
said switched line by detecting the calling party identification
(cpi), looking up the associated virtual logic address code,
displaying status of the calling party as ringing, and connecting
the trunk line to a console on which a line key corresponding to
the calling party is actuated.
7. A method of making and receiving telephone calls on a
multi-party key telephone system using switched lines including
line keys at operator consoles and line cards at outside line
terminations including the steps of:
maintaining in memory the association between line keys and
telephone numbers of parties that can be called or from whom calls
can be received;
receiving telephone calls by
determining the caller telephone number,
determining which line keys are associated with said caller
telephone number and indicating the line status as "ringing",
connecting the line card for the incoming call to the console at
which a line key associated with the calling party is actuated,
and
making telephone calls by
determining the telephone number of the party to be called
associated with an actuated line key
automatically dialing said telephone number associated with an
actuated line key, and
connecting the line card used for said call to the console at which
the line key was actuated.
8. A method of making and receiving telephone calls on a
multi-party key telephone system using switched lines wherein said
system includes line keys at consoles and trunk lines connected to
line cards,
maintaining a look-up table associating line keys with address
codes associated with parties that may be called,
maintaining a look-up table associating address codes and telephone
numbers for parties that may be called,
placing outgoing calls by
actuating a key corresponding to the party to be called
looking up the address code and corresponding telephone number of
the party corresponding to the actuated key and automatically
placing a call to said corresponding telephone number; and
receiving telephone calls
determining the caller telephone number,
looking up the address code associated with said caller telephone
number,
indicating "ringing" by the caller,
connecting the incoming line to the console where a line key is
actuated corresponding to said address code of said caller.
.Iadd.
9. A virtual private line key telephone system comprising:
a console including a plurality of line keys that can be associated
with a party that can be reached via a switched trunk line;
a look-up table for maintaining an association of line keys with
telephone numbers and parties to be associated;
means for determining the telephone number of incoming calls and
comparing an incoming call telephone number with telephone numbers
in said look-up table to indicate the caller at all line keys
associated with the incoming call; and
means coupling the incoming call to a console when a line key
associated with the incoming caller at the console is
actuated..Iaddend..Iadd.
10. A method of making and receiving telephone calls on a
multi-party key telephone system using switched lines including
line keys at operator consoles and line cards at outside line
terminations including the steps of:
maintaining an association between line keys, telephone numbers and
parties that can be called or from whom calls can be received;
receiving telephone calls by determining the caller telephone
number and indicating the line status as "ringing" at line keys
associated with the caller;
connecting the line card for the incoming call to the console at
which a line key associated with the calling party is actuated;
and
making telephone calls by determining the telephone number of the
party to be called associated with an actuated line key,
automatically dialing said telephone number associated with an
actuated line key, and connecting the line card for said call to
the console at which the line key was actuated..Iaddend.
Description
This is a Reissue of U.S. Pat. No. 5,214,691..Iaddend.
This invention relates to key telephone systems and, more
particularly, to the large key telephones of the type used in the
financial community referred to as trader turrets.
BACKGROUND OF THE INVENTION
In the financial community, securities and commodities are usually
traded using a private line trading network between brokerage
houses, banks, and other trading partners. A brokerage house, for
example, typically has one or more trading rooms coupled to a large
number of telephone lines, usually private lines, going to its
trading partners. A trading room may include any number of trading
stations each including a key telephone known as a "trader turret"
which provides key line access to a large number of the incoming
lines. A large trading room can easily trade securities and
commodities at the rate of millions of dollars per second.
A typical trading transaction involves a rapid series of short
telephone conversations to locate traders having the desired
security for sale at the best price. A typical call lasts ten
seconds and there may be on the order of five calls per minute
during the course of a single transaction. Private line key
telephone systems provide immediate access and are preferred for
the rapid, multi-call communications involved in most financial
transactions.
Manual dialing is much too slow and cumbersome to be seriously
considered in the hectic environment of financial trading. Auto
dial systems where a single key actuation sends dial tones or
pulses to a central office switch are also too slow for most
trading operations since dial pulse systems usually take about
eighteen seconds to connect, whereas tone systems usually take
about fourteen seconds to connect. Private lines provide the
desired immediate communication, but are much more expensive than
switched lines.
The trader turret work stations are specially designed to suit the
needs of a financial trader. The line key assignments on the
console are a personal matter and may change as market conditions
change. Typically a trader will want the most frequently called
trading partners to appear at a specific line key and at specific
locations on the console so that, in most cases, it is not
necessary to take time to read the legends associated with the
keys. The console must indicate the line status for all lines
available at the console so the trader can tell which lines are
in-use, on hold, ringing, or free. The console must also indicate
the active line at the console so that the trader can always
confirm the identity of the trading partner on the line.
An auto-dial line is not compatible with normal trader turret
operations. With a switched line the central office switch selects
the first available trunk to the trading room which means that the
call from a particular trading partner can come in on a number of
different lines. As a result, the call can appear at different
locations on the trader turret which is generally unacceptable to
traders. In addition, as previously mentioned, auto-dial lines take
too long to complete a connection.
SUMMARY OF THE INVENTION
An object of this invention is to provide a trader turret with
virtual private lines, i.e. switched lines that appear to the
trader as private lines.
Another object of the invention is to provide a less expensive
trading network based at least in part upon the use of switched
lines.
Most telephone service companies provide ISDN (Integrated Service
Digital Network) which consists of lines suitable for data
transmission that are switched at the central office. The central
office ISDN switch responds to a burst of data identifying the
party being called and the originating party. Normally, a
connection is completed in less than two seconds. On incoming calls
the central office switch provides the calling party identification
(cpi), i.e., the telephone number of the calling party. Because of
the short connection time specification, ISDN lines can be used in
the hectic financial trading operation. The ISDN lines cannot match
the speed of a private line, but are considerably less expensive
and are satisfactory for many of the less active trading
partners.
A separate key on the trader turret identifies each trading partner
that can be reached on the ISDN network in the system according to
the invention. A look-up table maintains the telephone number of
each of these parties and associates each such number with a line
key for the party. For outgoing calls this telephone number from
the look-up table is sent to the central office as a burst of data
when the key is actuated. The indicators associated with the ISDN
party line keys at all consoles in the trading room emulate the
private line indications.
Incoming calls from an ISDN party are more difficult to process
since the calls come in on common trunk lines which are not unique
for a particular trading partner as is the case with a private
line. An incoming ISDN call, however, does supply a calling party
identification (cpi) which identifies the caller and can be
compared with the look-up table containing the numbers of the ISDN
parties that the system is set up to receive. If a match is found,
a ringing line indication appears at all consoles associated with
the keys for the calling party. If a key is actuated, a path is
completed from the incoming call trunk line to the trader turret at
which the key was actuated and the indicators at the consoles are
changed to indicate that the line is in-use.
The only difference observable by the trader between a private line
and a virtual ISDN private line according to this invention is a
slightly greater connection time for the outgoing virtual private
line calls. The signalling at the console emulates a private line
and therefore IDSN lines are satisfactory for many financial
trading operations.
GENERAL DESCRIPTION OF THE DRAWINGS
The foregoing and other objects may be understood more fully from
the following specification which sets forth an illustrative
embodiment of the invention. The drawings are part of the
specification wherein:
FIG. 1 is a block diagram of the overall system according to the
invention;
FIG. 2 is a time line diagram of events in setting up an incoming
virtual private line call;
FIG. 3 is a time line diagram of events in setting up an outgoing
virtual private line call;
FIG. 4 is a flow diagram of the program at the trader work station;
and
FIG. 5 is a flow diagram of the program at the ISDN line card.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall diagram illustrating the system according to
the invention. A trading room includes any desired number of trader
work stations 10 each including a large number of line keys 12. A
typical trader work station will have at least thirty line keys and
may have as many as several hundred line keys. In a normal
installation, actuation of a line key establishes a talk path from
a handset 22 at the work station to the associated private line 20
via a suitable switch 24.
Associated with each of the line keys at the work station is a pair
of indicating lamps 14 and 16. Lamp 14 may be a green status
indicator which indicates the line is busy by a steady on
condition, the line is ringing by a rapid flashing, the line is on
hold by a slow flashing, or the line is free by the off condition.
The other lamp 16 of each pair has a different color, such as red
or amber, and is used to indicate the active line that is in use at
the station. Also associated with each line key is a name plate
indicator 18 which is preferably an LCD display identifying the
party associated with the line key.
Trader work station 10 is controlled by a microprocessor 30 which
has access to a key press sensor 31, a lamp display memory 32, a
name display memory 33, a line status memory 36, a line register
37, and a line key table 34. Key press sensor 31 detects when a
line key is depressed so that when interrogated by the
microprocessor, the sensor returns a digital code identifying the
depressed key. The lamp display memory includes a memory bit for
each indicator lamp 14 and 16 which control the on/off state of the
respective lamps. The microprocessor periodically updates the lamp
display memory according to the current line status and active
line. The line status memory 36 includes data indicating the
current status of all the lines in the trading network. Line key
table 34 includes the data for the custom key set up for the work
station giving for each key the associated logic address code (LAC)
for the line to be connected when the key is depressed, and the
name plate information for the key. Thus, the Line Key table
associates the parties with specific line keys at specific
locations on the console.
The microprocessor uses the line status information in memory 36
and the line key to line assignment information in table 34 to
update the lamp display memory 32 so that the work station displays
line status at the correct location on the console. The
microprocessor updates the name display memory 33 according to the
name assignments in table 34. With this arrangement the trader can
have any line in the system appear at any desired line key with any
desired name plate designation by the appropriate set up of table
34.
Handset 22 provides, and responds to, analog signals. The handset
is therefore coupled to digital switch 24 via an analog to digital
converter 38. Microprocessor 30 supplies commands to the switch for
establishing a talk path to a line card selected by actuating a
line key.
Each of the private lines 20 available to the network connects to
switch 24 via a line card 21 constructed according to the
specifications for the particular line. The line cards include
conventional line status circuits 28 which detect the status of the
line, that is, busy, ringing, hold, or free. The line status
circuits pass on digital signals indicating status to
microprocessor 29 in the line card which, in turn, supplies the
information to all the line status memories 36 at the turret work
stations via a broadcast channel 26. Preferably, only changes in
line status are broadcast to thereby reduce the traffic on the
broadcast channel. With such an arrangement, the interface card 35
at the work station must decode the line status change information
received from the broadcast channel and update the line status
memory 36 accordingly.
If the private line is of the analog type, the signal is passed
through an analog to digital conversion and then to microprocessor
29 for routing to a particular handset at a work station via switch
24.
Switch 24 is preferably a duplex digital switch including a
broadcast channel of the type described in application Ser. No.
07/766,047, entitled "Distributed Control Switching Network for
Multi-line Telephone Communication" filed concurrently herewith.
This switch is modular with each switch element being controlled by
separate processors. A typical switch element includes 19 input
ports and 19 output ports with 32 channels per port. For routing
through the switch, each destination is given a unique logic
address code (LAC). A route is selected by supplying the switch
with a "path set" command and the destination LAC. When a switch
element receives a "path set", command it interprets the LAC and
sets a path through the switch element toward the destination LAC.
To permit unlimited conferencing, a talk path is established by
first connecting the work station to a bridge and then establishing
the route from the line card back to that bridge.
The preferred switch also includes a dedicated broadcast channel in
each switch element. Preferably each switch element includes a
first-in, first-out (FIFO) stack for received broadcast messages so
that multiple broadcast messages can be prioritized when passing
through a switch.
For selection of a private line, the operator locates a line that
is free or ringing and depresses the appropriate line key. The
microprocessor looks up the LAC for the line corresponding to the
depressed key in line table 34. A path set command is issued to
switch 24 to establish a path between handset 22 and the
appropriate private line card 21. When the connection is
established, line status circuit 28 detects the change of status to
busy and broadcasts this status change to all the line status
memories 36 in the network. Work station microprocessor 30, using
table 34, changes the status and active line indicators associated
with the depressed key.
The purpose of this invention is to provide switched line
capability that emulates private line operation at the trader work
station. In particular, it is important that the switched line
party always appear at the same location on the console and always
be associated with the same line key regardless of which switched
line is used for the call.
Although ISDN switched data lines are preferred because of their
high operating speeds, other types of switched lines could also be
used provided caller identification is provided on incoming calls.
Also systems similar to ISDN in other countries, such as Digital
Access Signalling (DAS) in the United Kingdom, can also be used.
The ISDN protocols are set forth, for example, in ISDN Protocols
for Connection Control by Harmon and Newman, 1989 IEEE. Basically,
ISDN lines provide data in packets including a header giving the
calling party identifier (cpi). The ISDN line card 40 must be
designed in accordance with the ISDN protocol.
Line card 40 includes line status circuits 45 which determine the
status of ISDN line 47 and supply the status information to a
microprocessor 41. Since the incoming data is in a serial format,
it is supplied to a shift register for conversion to a parallel
format supplied to the microprocessor. The microprocessor is
programmed to extract the calling party identifier (cpi) from the
incoming data and stores this information in a cpi register 44.
The ISDN line card includes a CPI Table (look-up table) 42
accessible to the microprocessor. The table includes all the cpi
telephone numbers that the system will recogmze and the associated
virtual logic address codes (vLAC). The VLAC is a dummy address
code used to identify a party available on an ISDN line as though
it were a private line party. A VLAC serves to identify a line key
associated with an ISDN party rather than the line to that party.
For incoming calls, the CPI Table is used to convert the cpi into a
VLAC so that line status indications appear at the appropriate
locations on the consoles associated with the particular line key
and calling party. For outgoing calls, the CPI Table is used to
connect the VLAC message into the telephone number to be called. In
actual practice, the use of separate look-up tables for incoming
and outgoing calls would usually be preferable.
The ISDN line card also includes a VLAC/aLAC register 43 for
associating the ISDN party with the actual LAC of the ISDN line
card. Microprocessor 41 is coupled to switch 24 via the broadcast
channel 26 and a data channel 48.
For virtual private line communication, a line register 37 is added
to the memory accessible to microprocessor 30 for storing the
VLAC/ALAC association for a call which is the same as that in
register 43. For the virtual private line keys, the VLAC for the
virtual party is inserted in LINE KEY table 34 instead of the LAC
identifying an actual line.
With this arrangement, line status information is broadcast to the
trader work station according to the VLAC and is therefore
displayed on the console at the first location associated with the
ISDN party rather than with the line being used. When a talk path
is established, the talk path is from the work station to the ISDN
line (ALAC) associated with the virtual party (VLAC).
FIG. 2 is a time line diagram illustrating the events taking place
in the ISDN line card (located at ALAC) and at the work station
card (bLAC), as well the communication between these cards.
The time sequence working from top to bottom in the diagram
commences at the line card with detection of an incoming call which
includes a calling party identification (cpi). In step 50 of FIG. 2
the line card processor looks up the VLAC corresponding to the cpi
of the incoming call from the CPI Table 42 and associates the VLAC
and ALAC in register 43 (FIG. 1). The line card next broadcasts the
VLAC and ALAC and indicates the status thereof as "ringing". The
broadcast information is conveyed to all of the trader work
stations and the line status memory 36 at the work station is
updated accordingly. In step 51, at the work station card, the lamp
display is updated to indicate the status as ringing for the line
key corresponding to the VLAC. This ringing signal identifies the
calling party on the ISDN line rather than the calling private line
as is normally the case.
If the operator decides to pick up the ringing line by depressing
the corresponding line key, the work station card connects the talk
path to the associated bridge (BLAC) and initiates a "path-set"
request to the BLAC. The call request is sent to the ALAC line card
which then prepares instructions in step 53 to initiate a "path
set" form the line card (ALAC) to the work station (BLAC). Switch
24 (FIG. 1) then establishes a duplex talk path from the line card
(ALAC) to the work station bridge (BLAC). The line card also sends
out a status broadcast identifying the ALAC, the VLAC and the
status as "busy". The broadcast information is received by all work
stations which update the local line status memory and, in step 54,
display the indicator lamps corresponding to the VLAC as "busy". At
his point the communication has been established between the
calling party and the work station hand set, and the line key for
the calling part is indicated as "busy" at all of the work stations
which access that party.
When a call is completed, a release can be initiated either by the
calling party or the operator of the work station. In either event
a command is sent to the switch to "drop" the talk path. In steps
55 and 56 the work station and the line card both disassociate the
ALAC from the VLAC and the line card thereafter broadcasts the
ALAC, the VLAC, and their status as "free". In step 57 the
operation is completed by a display at the work station of the
indicator light associated with the VLAC line key as "free".
FIG. 3 is a similar time line diagram for the events which take
place in an ongoing virtual private line call. In this case the
initial step is a line key press at the work station when the
operator wishes to place a call to one of the ISDN parties. When
the key is depressed, the microprocessor in the work station looks
up the VLAC in Table 34 corresponding to the depressed line key and
also looks up a free ISDN line (ALAC) in status memory 36. In step
61 the work station is then connected to the associated bridge
(BLAC). A request for a call set up giving the BLAC address is then
sent to the ISDN line card corresponding to the selected ALAC. The
line card looks up the called party identification (cpi)
corresponding to the VLAC and sets up the call with central office
switching. In step 62 the line card then initiates a "path set"
from the ALAC back to the BLAC and establishes a duplex
communication therebetween via switch 24 (FIG. 1). The line card
next will broadcast the VLAC, the ALAC, and the line status as
"busy".
When the call is terminated, either by release at the work station
or a release at the line card, the path through the switch is
dropped and the ALAC and VLAC are disassociated in steps 63 and 64.
Finally, the line card sends out a broadcast of the VLAC, the ALAC
and indicates the line status as being "free".
The flow diagram for the microprocessor program at the work station
is illustrated in FIG. 4. The program begins with step 71 which is
a look-up of the status of line LACs and vLACs for display on the
station consoles. The program also periodically interrogates the
key press sensor to determine if a line key has been pressed
corresponding to a virtual private line (VLAC). If the answer in
decision 72 is "no", the program proceeds to handle other line
events as required. If decision 72 indicates that a key has been
depressed corresponding to a virtual private line party, the
processor in step 73 looks up the VLAC number for the depressed key
in the Line Key Table. The processor then looks up a free ISDN line
(ALAC) in the line status memory 36. The ALAC and VLAC are then
associated and stored in line register 37. In step 76 the processor
next sets up a connection to the local bridge (BLAC) and in step 77
sends out a request to the ALAC line card to set up a path back to
the bridge (BLAC). The program then monitors acknowledgements to
determine if the call set up has been received by the line card. If
not, the program waits in step 79 and then repeats steps 76 and 77
attempting to again set up the call back to the bridge (BLAC). When
the call set up has been acknowledged, the program proceeds to step
81 which handles the call progressing as required. The program
periodically checks to determine if the call has been terminated
and, if not, repeats step 81. When the call is terminated, as
indicated by decision 82, the program proceeds in step 83 to
disassociate the ALAC from the VLAC and then returns to the idle
condition.
FIG. 5 is a flow diagram for the program in the ISDN line card. In
this program the processor proceeds through inquiries 90-92 to
determine, successively, whether there is an incoming call, a call
set-up request, or a release. If all decisions are negative, the
program proceeds to step 93 where it continues line card
handling.
If decision 90 indicates that an incoming call is present, the
program proceeds to step 94 which extracts the calling party
identification (cpi) from the incoming call packet. The processor
in step 95 then looks up the VLAC corresponding to that cpi in the
CPI table. In step 96 the ALAC is associated with the VLAC and in
step 102 broadcasts the VLAC, the ALAC, and line status as
"ringing". If a call set up request is present at the time of
decision 91 (either as a new call or in response to a "running"
indication), the program proceeds to look up the cpi for the VLAC
in the CPI table in step 100 and sets up a call to the called party
corresponding to the cpi in step 101. Thereafter, the program
proceeds to initiate the path set up and broadcasts the line status
in steps 97 and 98.
If a release is detected in decision 92, the program proceeds to
drop the talk path in step 104 and disassociates the ALAC from the
VLAC in step 105. Thereafter, the processor is step 106 broadcasts
that the VLAC and ALAC line status is "free".
While only one illustrative embodiment of the structure and methods
has been described in detail, it should be obvious that there are
numerous variations within the scope of the invention. The
invention is more particularly defined in the appended claims.
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