U.S. patent application number 13/725031 was filed with the patent office on 2013-05-09 for systems and methods for facilitating push-to-talk (ptt) communications using sip-based messaging.
This patent application is currently assigned to RESEARCH IN MOTION LIMITED. The applicant listed for this patent is RESEARCH IN MOTION LIMITED. Invention is credited to Alexander SHATSKY.
Application Number | 20130115996 13/725031 |
Document ID | / |
Family ID | 42631435 |
Filed Date | 2013-05-09 |
United States Patent
Application |
20130115996 |
Kind Code |
A1 |
SHATSKY; Alexander |
May 9, 2013 |
SYSTEMS AND METHODS FOR FACILITATING PUSH-TO-TALK (PTT)
COMMUNICATIONS USING SIP-BASED MESSAGING
Abstract
A method of facilitating push-to-talk (PTT) communications
between a server device and a client device using SIP-based
messaging, the server device being in communication with a media
server. The method includes receiving in the server device from the
client device a SUBSCRIBE message for subscription to a
push-to-talk group, the SUBSCRIBE message including media
information of the client device, storing in the server device the
media information of the client device, and sending from the server
device to the client device a NOTIFY message, the NOTIFY message
including media information of the media server for storage by the
client device.
Inventors: |
SHATSKY; Alexander;
(Vaughan, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RESEARCH IN MOTION LIMITED; |
Waterloo |
|
CA |
|
|
Assignee: |
RESEARCH IN MOTION LIMITED
Waterloo
CA
|
Family ID: |
42631435 |
Appl. No.: |
13/725031 |
Filed: |
December 21, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12392177 |
Feb 25, 2009 |
8374643 |
|
|
13725031 |
|
|
|
|
Current U.S.
Class: |
455/518 |
Current CPC
Class: |
H04M 7/121 20130101;
H04L 65/4061 20130101; H04M 3/4228 20130101; H04W 4/10 20130101;
H04W 76/12 20180201; H04M 2207/18 20130101; H04W 76/45
20180201 |
Class at
Publication: |
455/518 |
International
Class: |
H04W 4/10 20060101
H04W004/10 |
Claims
1. A method of facilitating push-to-talk (PTT) communications
between a server device and a client device using SIP-based
messaging, the server device being in communication with a media
server, the method comprising: sending to the server device from
the client device a SUBSCRIBE message for subscription to a
push-to-talk group, the SUBSCRIBE message including media
information of the client device for storage of the media
information in the server device; and establishing a PTT media
session between the media server and the client device based on the
stored media information of the client device.
2. The method of claim 1, further comprising: receiving in the
client device from the server device a NOTIFY message, the NOTIFY
message including media information of the media server; and
storing the media information of the media server in the client
device.
3. The method of claim 2, further comprising: sending to the server
device from the client device a second SUBSCRIBE message for
initiating the PTT media session, the second SUBSCRIBE message
excluding media information.
4. The method of claim 2, further comprising: receiving in the
client device from the server device a second NOTIFY message for
initiation of the PTT media session, the second NOTIFY message
excluding media information.
5. The method of claim 2, wherein the media information of the
client device or the server device includes port information.
6. The method of claim 2, wherein the SUBSCRIBE or NOTIFY messages
include an event package relating to push-to-talk.
7. The method of claim 6, wherein the event package includes state
information of the push-to-talk group.
8. The method of claim 7, wherein the state information includes an
active state when implementing a PTT media session and an idle
state otherwise.
9. The method of claim 2, wherein the SUBSCRIBE or NOTIFY message
includes expiry information of the push-to-talk group
subscription.
10. The method of claim 1, wherein the client device comprises part
of an enterprise system.
11. A method of facilitating push-to-talk (PTT) communications
between a server device and a client device using SIP-based
messaging, the server device being in communication with a media
server, the method comprising: sending to the server device from
the client device a SUBSCRIBE message for subscription to a
push-to-talk group; receiving in the client device from the server
device a NOTIFY message, the NOTIFY message including media
information of the media server; storing the media information of
the media server in the client device; and establishing a PTT media
session between the media server and the client device using the
stored media information.
12. The method of claim 11 wherein the SUBSCRIBE message includes
media information of the client device for storage in the server
device.
13. The method of claim 12, further comprising: sending to the
server device from the client device a second SUBSCRIBE message for
initiating the PTT media session, the second SUBSCRIBE message
excluding media information.
14. The method of claim 12, wherein the media information of the
client device or the server device includes port information.
15. The method of claim 11, wherein the SUBSCRIBE or NOTIFY
messages include an event package relating to push-to-talk.
16. The method of claim 15, wherein the event package includes
state information of the push-to-talk group.
17. The method of claim 16, wherein the state information includes
an active state when implementing a PTT media session and an idle
state otherwise.
18. A client device for facilitating push-to-talk (PTT)
communications using SIP-based messaging with a server device, the
server device being in communication with a media server, the
client device comprising: a memory; a controller for accessing the
memory; a communications module for communicating with the server
device; and the controller being configured to: send to the server
device a SUBSCRIBE message for subscription to a push-to-talk
group, the SUBSCRIBE message including media information of the
client device, receive from the server device a NOTIFY message, the
NOTIFY message including media information of the media server,
store the media information of the media server in the memory, and
establish a PTT media session between the media server and the
client device using the stored media information of the media
server.
19. A client device for facilitating push-to-talk (PTT)
communications using SIP-based messaging with a server device, the
server device being in communication with a media server, the
client device comprising: a memory; a controller for accessing the
memory; a communications module for communicating with the server
device; and the controller being configured to: send to the server
device a SUBSCRIBE message for subscription to a push-to-talk
group, the SUBSCRIBE message including media information of the
client device for storage of the media information in the server
device; and establish a PTT media session between the media server
and the client device based on the stored media information of the
client device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/392,177 filed Feb. 25, 2009, the contents
of which are hereby incorporated by reference.
FIELD
[0002] The present application relates to push-to-talk systems and
methods, and in particular to implementing push-to-talk using
Session Initiation Protocol (SIP).
BACKGROUND
[0003] Push-to-talk (PTT) generally refers to real-time direct
one-to-one and one-to-group voice communication service, which may
occur in the cellular, Public Switch Telephone Networks (PSTN) and
Internet networks. PTT calls can be directed to both individuals
and talk groups. In a PTT call, the call connection is initiated by
an originator device while the receiver typically does not have to
"answer" the call.
[0004] PTT calls are one-way communications (half-duplex), which
means that while one person speaks the others listen. In a PTT
conversation, users typically no longer need to make several calls
to coordinate with a group.
[0005] PTT service users are typically engaged in some other
activity than a telephone call, and they listen to the group
traffic during their activity. A user is usually contacted by
receiving a PTT call from a member of the PTT group and can respond
to the PTT group with a push of a key.
[0006] Session Initiation Protocol (SIP) is a protocol which is
based on a request-response model. SIP leaves open the particular
implementation of the desired functionality, and for example does
not provide for specific implementation of PTT. As the
interpretation remains open, some implementations of PTT using SIP
may lead to inefficiencies.
[0007] For example, in some conventional systems implementing PTT
using SIP, media parameters are negotiated and communicated only
once the PTT call is initiated by a user. This wastes resources and
time between when the user actually initiates the PTT call and when
the system connects the user to the receiving units. Call lags may
occur each time a user initiates a PTT call. Further, such
inefficiencies become magnified when the PTT group involves a large
number of parties.
[0008] Other difficulties with existing conventional systems will
be apparent to those skilled in the art in view of the detailed
description below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Reference will now be made, by way of example, to the
accompanying drawings which show example embodiments, and in
which:
[0010] FIG. 1 shows, in block diagram form, an example system for
managing enterprise-related mobile calls, including an enterprise
communications platform, to which example embodiments may be
applied;
[0011] FIG. 2 shows, in block diagram form, further details of an
embodiment of the enterprise communications platform;
[0012] FIG. 3 shows another embodiment of the enterprise
communications platform;
[0013] FIG. 4 shows yet another embodiment of the enterprise
communications platform;
[0014] FIG. 5 shows further details of the enterprise
communications platform of FIG. 3;
[0015] FIG. 6 shows, in block diagram form, an example push-to-talk
system and associated push-to-talk procedure implemented by the
system of FIG. 1;
[0016] FIG. 7 shows, in block diagram form, an example push-to-talk
subscription procedure between a client device and a server device
implemented prior to the push-to-talk procedure in the push-to-talk
system of FIG. 6;
[0017] FIG. 8 shows an example message to be used between devices
within the push-to-talk procedures of FIGS. 6 to 7;
[0018] FIG. 9 shows an example message from the client device to
the server device in the subscription procedure of FIG. 8;
[0019] FIG. 10 shows an example message from the sever device to
the client device in the subscription procedure of FIG. 8;
[0020] FIG. 11 shows an example message from an originator client
device initiating a push-to-talk session within the push-to-talk
procedure of FIG. 7; and
[0021] FIG. 12 shows an example message from a server device to
receiving client devices within the push-to-talk procedure of FIG.
7.
[0022] Similar reference numerals may have been used in different
figures to denote similar components.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[0023] In one aspect, there is provided a method of facilitating
push-to-talk (PTT) communications between a server device and a
client device using SIP-based messaging, the server device being in
communication with a media server. The method includes: receiving
in the server device from the client device a SUBSCRIBE message for
subscription to a push-to-talk group, the SUBSCRIBE message
including media information of the client device, storing in the
server device the media information of the client device, and
initiating, based on receipt in the server device of a second
SUBSCRIBE message for initiating a push-to-talk session, a media
session between the media server and the client device using the
stored media information.
[0024] In another aspect, there is provided a method of
facilitating push-to-talk (PTT) communications between a server
device and a client device using SIP-based messaging, the server
device being in communication with a media server. The method
includes: receiving in the server device from the client device a
SUBSCRIBE message for subscription to a push-to-talk group, sending
from the server device to the client device a NOTIFY message, the
NOTIFY message including media information of the media server for
storage by the client device, and initiating, based on receipt in
the server device of a second SUBSCRIBE message for initiating a
push-to-talk session, a media session between the media server and
the client device using the stored media information.
[0025] In yet another aspect, there is provided a server device for
facilitating push-to-talk (PTT) communications using SIP-based
messaging. The server device includes a memory, a controller for
accessing the memory, a communications module in communications
with the controller for communicating with a media server and a
client device. The controller is configured to: receive from the
client device a SUBSCRIBE message for subscription to a
push-to-talk group, the SUBSCRIBE message including media
information of the client device, store in memory the media
information of the client device, send to the client device a
NOTIFY message, the NOTIFY message including media information of
the media server for storage by the client device, and initiate,
based on receipt of a second SUBSCRIBE message for initiating a
push-to-talk session, a media session between the media server and
the client device using the stored media information.
[0026] In yet another aspect, there is provided a system for
facilitating push-to-talk (PTT) communications using SIP-based
messaging. The system includes a media server, a server device in
communication with the media server, and at least one PTT receiving
client devices, each for sending to the server device a SUBSCRIBE
message for subscription to a push-to-talk group, the SUBSCRIBE
message including media information of each of the PTT receiving
client devices. The system further includes a PTT originator client
device for sending to the server device a SUBSCRIBE message for
subscription to a push-to-talk group. The server device is
configured to: store the media information of the PTT-receiving
client devices, and send to the PTT originator client device a
NOTIFY message, the NOTIFY message including media information of
the media server. The PTT originator client device is configured to
store the media information of the media server. The server device
is further configured to, upon receipt in the server device from
the PTT originator client device of a second SUBSCRIBE message for
initiating a push-to-talk session, initiate a media session between
the media server and the client devices using the stored media
information.
[0027] Other aspects will be apparent to those of ordinary skill in
the art from a review of the following detailed description in
conjunction with the drawings.
[0028] The present application relates to the control and
management of push-to-talk (PTT) communications. Although reference
may be made to "calls" and "talk" in the description of example
embodiments below, it will be appreciated that the described
systems and methods are applicable to session-based communications
in general and not limited to voice calls. Reference to calls may
for example include voice calls as well as media sessions which may
for example include video and/or audio.
[0029] Reference is now made to FIG. 1, which shows, in block
diagram form, an example system, generally designated 10, for the
control and management of communications. The system 10 includes an
enterprise or business system 20, which in many embodiments
includes a local area network (LAN). In the description below, the
enterprise or business system 20 may be referred to as an
enterprise network 20. It will be appreciated that the enterprise
network 20 may include more than one network and may be located in
multiple geographic areas in some embodiments.
[0030] The enterprise network 20 may be connected, often through a
firewall 22, to a wide area network (WAN) 30, such as the Internet.
The enterprise network 20 may also be connected to a public
switched telephone network (PSTN) 40 via direct inward dialing
(DID) trunks or primary rate interface (PRI) trunks.
[0031] The enterprise network 20 may also communicate with a public
land mobile network (PLMN) 50, which may also be referred to as a
wireless wide area network (WWAN) or, in some cases, a cellular
network. The connection with the PLMN 50 may be made via a relay
26, as known in the art.
[0032] The enterprise network 20 may also provide a wireless local
area network (WLAN) 32a featuring wireless access points. Other
WLANs 32 may exist outside the enterprise network 20. For example,
WLAN 32b may be connected to WAN 30.
[0033] The system 10 may include a number of enterprise-associated
mobile devices 11 (only one shown). The mobile devices 11 may
include devices equipped for cellular communication through the
PLMN 50, mobile devices equipped for Wi-Fi communications over one
of the WLANs 32, or dual-mode devices capable of both cellular and
WLAN communications. WLANs 32 may be configured in accordance with
one of the IEEE 802.11 specifications.
[0034] It will be understood that the mobile devices 11 include one
or more radio transceivers and associated processing hardware and
software to enable wireless communications with the PLMN 50 and/or
one of the WLANs 32. In various embodiments, the PLMN 50 and mobile
devices 11 may be configured to operate in compliance with any one
or more of a number of wireless protocols, including GSM, GPRS,
CDMA, EDGE, UMTS, EvDO, HSPA, 3GPP, or a variety of others. It will
be appreciated that the mobile device 11 may roam within the PLMN
50 and across PLMNs, in known manner, as the user moves. In some
instances, the dual-mode mobile devices 11 and/or the enterprise
network 20 are configured to facilitate roaming between the PLMN 50
and a WLAN 32, and are thus capable of seamlessly transferring
sessions (such as voice calls) from a connection with the cellular
interface of the dual-mode device 11 to the WLAN 32 interface of
the dual-mode device 11, and vice versa.
[0035] The enterprise network 20 typically includes a number of
networked servers, computers, and other devices. For example, the
enterprise network 20 may connect one or more desktop or laptop
computers 15 (one shown). The connection may be wired or wireless
in some embodiments. The enterprise network 20 may also connect to
one or more digital telephone sets 17 (one shown).
[0036] The enterprise network 20 may include one or more mail
servers, such as mail server 24, for coordinating the transmission,
storage, and receipt of electronic messages for client devices
operating within the enterprise network 20. Typical mail servers
include the Microsoft Exchange Server.TM. and the IBM Lotus
Domino.TM. server. Each user within the enterprise typically has at
least one user account within the enterprise network 20. Associated
with each user account is message address information, such as an
e-mail address. Messages addressed to a user message address are
stored on the enterprise network 20 in the mail server 24. The
messages may be retrieved by the user using a messaging
application, such as an e-mail client application. The messaging
application may be operating on a user's computer 15 connected to
the enterprise network 20 within the enterprise. In some
embodiments, the user may be permitted to access stored messages
using a remote computer, for example at another location via the
WAN 30 using a VPN connection. Using the messaging application, the
user may also compose and send messages addressed to others, within
or outside the enterprise network 20. The messaging application
causes the mail server 24 to send a composed message to the
addressee, often via the WAN 30.
[0037] The relay 26 serves to route messages received over the PLMN
50 from the mobile device 11 to the corresponding enterprise
network 20. The relay 26 also pushes messages from the enterprise
network 20 to the mobile device 11 via the PLMN 50.
[0038] The enterprise network 20 also includes an enterprise server
12. Together with the relay 26, the enterprise server 12 functions
to redirect or relay incoming e-mail messages addressed to a user's
e-mail address within the enterprise network 20 to the user's
mobile device 11 and to relay incoming e-mail messages composed and
sent via the mobile device 11 out to the intended recipients within
the WAN 30 or elsewhere. The enterprise server 12 and relay 26
together facilitate "push" e-mail service for the mobile device 11
enabling the user to send and receive e-mail messages using the
mobile device 11 as though the user were connected to an e-mail
client within the enterprise network 20 using the user's
enterprise-related e-mail address, for example on computer 15.
[0039] As is typical in many enterprises, the enterprise network 20
includes a Private Branch eXchange (although in various embodiments
the PBX may be a standard PBX or an IP-PBX, for simplicity the
description below uses the term PBX to refer to both) 16 having a
connection with the PSTN 40 for routing incoming and outgoing voice
calls for the enterprise. The PBX 16 is connected to the PSTN 40
via DID trunks or PRI trunks, for example. The PBX 16 may use ISDN
signaling protocols for setting up and tearing down
circuit-switched connections through the PSTN 40 and related
signaling and communications. In some embodiments, the PBX 16 may
be connected to one or more conventional analog telephones 19. The
PBX 16 is also connected to the enterprise network 20 and, through
it, to telephone terminal devices, such as digital telephone sets
17, softphones operating on computers 15, etc. Within the
enterprise, each individual may have an associated extension
number, sometimes referred to as a PNP (private numbering plan), or
direct dial phone number. Calls outgoing from the PBX 16 to the
PSTN 40 or incoming from the PSTN 40 to the PBX 16 are typically
circuit-switched calls. Within the enterprise, e.g. between the PBX
16 and terminal devices, voice calls are often packet-switched
calls, for example Voice-over-IP (VoIP) calls.
[0040] The enterprise network 20 may further include a Service
Management Platform (SMP) 18 for performing some aspects of
messaging or session control, like call control and advanced call
processing features. The SMP 18 may, in some cases, also perform
some media handling. Collectively the SMP 18 and PBX 16 may be
referred to as the enterprise communications platform, generally
designated 14. It will be appreciated that the enterprise
communications platform 14 and, in particular, the SMP 18, is
implemented on one or more servers having suitable communications
interfaces for connecting to and communicating with the PBX 16
and/or DID/PRI trunks. Although the SMP 18 may be implemented on a
stand-alone server, it will be appreciated that it may be
implemented into an existing control agent/server as a logical
software component. As will be described below, the SMP 18 may be
implemented as a multi-layer platform.
[0041] The enterprise communications platform 14 implements the
switching to connect session legs and may provide the conversion
between, for example, a circuit-switched call and a VoIP call, or
to connect legs of other media sessions. In some embodiments, in
the context of voice calls the enterprise communications platform
14 provides a number of additional functions including automated
attendant, interactive voice response, call forwarding, voice mail,
etc. It may also implement certain usage restrictions on enterprise
users, such as blocking international calls or 1-900 calls. In many
embodiments, Session Initiation Protocol (SIP) may be used to
set-up, manage, and terminate media sessions for voice calls. Other
protocols may also be employed by the enterprise communications
platform 14, for example, Web Services, Computer Telephony
Integration (CTI) protocol, Session Initiation Protocol for Instant
Messaging and Presence Leveraging Extensions (SIMPLE), and various
custom Application Programming Interfaces (APIs), as will be
described in greater detail below.
[0042] One of the functions of the enterprise communications
platform 14 is to extend the features of enterprise telephony to
the mobile devices 11. For example, the enterprise communications
platform 14 may allow the mobile device 11 to perform functions
akin to those normally available on a standard office telephone,
such as the digital telephone set 17 or analog telephone set 15.
Example features may include direct extension dialing, enterprise
voice mail, conferencing, call transfer, call park, etc.
[0043] Reference is now made to FIGS. 2 to 4, which show example
embodiments of the enterprise communications system 14. FIG. 2
illustrates an embodiment intended for use in a circuit-switched
TDM context. The PBX 16 is coupled to the SMP 18 via PRI connection
60 or other suitable digital trunk. In some embodiments, the PRI
connection 60 may include a first PRI connection, a second PRI
connection, and a channel service unit (CSU), wherein the CSU is a
mechanism for connecting computing devices to digital mediums in a
manner that allows for the retiming and regeneration of incoming
signals. It will be appreciated that there may be additional or
alternative connections between the PBX 16 and the SMP 18.
[0044] In this embodiment, the SMP 18 assumes control over both
call processing and the media itself. This architecture may be
referred to as "First Party Call Control". Many of the media
handling functions normally implemented by the PBX 16 are handled
by the SMP 18 in this architecture. Incoming calls addressed to any
extension or direct dial number within the enterprise, for example,
are always first routed to the SMP 18. Thereafter, a call leg is
established from the SMP 18 to the called party within the
enterprise, and the two legs are bridged. Accordingly, the SMP 18
includes a digital trunk interface 62 and a digital signal
processing (DSP) conferencing bridge 64. The DSP conferencing
bridge 64 performs the bridging of calls for implementation of
various call features, such as conferencing, call transfer, etc.
The digital trunk interface 62 may be implemented as a plurality of
telephonic cards, e.g. Intel Dialogic cards, interconnected by a
bus and operating under the control of a processor. The digital
trunk interface 62 may also be partly implemented using a processor
module such as, for example, a Host Media Processing (HMP)
processor.
[0045] The SMP 18 may include various scripts 66 for managing call
processing. The scripts 66 are implemented as software modules,
routines, functions, etc., stored in non-volatile memory and
executed by the processor of the SMP 18. The scripts 66 may
implement call flow logic, business logic, user preferences, call
service processes, and various feature applications.
[0046] FIG. 3 shows another embodiment in which the PBX 16 performs
the functions of terminating and/or bridging media streams, but
call control functions are largely handled by the SMP 18. In this
embodiment, the SMP 18 may be referred to as a call control server
18. This architecture may be referred to as "Third-Party Call
Control".
[0047] The call control server 18 is coupled to the PBX 16, for
example through the LAN, enabling packet-based communications and,
more specifically, IP-based communications. In one embodiment,
communications between the PBX 16 and the call control server 18
are carried out in accordance with SIP. In other words, the call
control server 18 uses SIP-based communications to manage the set
up, tear down, and control of media handled by the PBX 16. In one
example embodiment, the call control server 18 may employ a
communications protocol conforming to the ECMA-269 or ECMA-323
standards for Computer Supported Telecommunications Applications
(CSTA).
[0048] FIG. 4 shows yet another embodiment of the enterprise
communications system 14. This embodiment reflects the adaptation
of an existing set of call processing scripts to an architecture
that relies on third-party call control, with separate call control
and media handling. The SMP 18 includes a call processing server
74. The call processing server 74 includes the scripts or other
programming constructs for performing call handling functions. The
SMP 18 also includes a SIP server 72 and a media server 76. The
separate SIP server 72 and media server 76 logically separate the
call control from media handling. The SIP server 72 interacts with
the call processing server 74 using a computer-implemented
communications handling protocol, such as one of the ECMA-269 or
ECMA-323 standards. These standards prescribe XML based messaging
for implementing Computer Supported Telecommunications Applications
(CSTA).
[0049] The SIP server 72 interacts with the media server 76 using
SIP-based media handling commands. For example, the SIP server 72
and media server 76 may communicate using Media Server Markup
Language (MSML) as defined in IETF document Saleem A., "Media
Server Markup Language", Internet Draft, draft-saleem-msml-07, Aug.
7, 2008. The media server 76 may be configured to perform Host
Media Processing (HMP).
[0050] Other architectures or configurations for the enterprise
communications system 14 will be appreciated by those ordinarily
skilled in the art.
[0051] Reference is now made to FIG. 5, which shows another
embodiment of the enterprise communications system 14 with a Third
Party Call Control architecture. In this embodiment, the SMP 18 is
a multi-layer platform that includes a protocol layer 34, a
services layer 36 and an application layer 38. The protocol layer
34 includes a plurality of interface protocols configured for
enabling operation of corresponding applications in the application
layer 38. The services layer 36 includes a plurality of services
that can be leveraged by the interface protocols to create richer
applications. Finally, the application layer 38 includes a
plurality of applications that are exposed out to the communication
devices and that leverage corresponding ones of the services and
interface protocols for enabling the applications.
[0052] Specifically, the protocol layer 34 preferably includes
protocols which allow media to be controlled separate from data.
For example, the protocol layer 34 can include, among other things,
a Session Initiation Protocol or SIP 80, a Web Services protocol
82, an Application Programming Interface or API 84, a Computer
Telephony Integration protocol or CTI 86, and a Session Initiation
Protocol for Instant Messaging and Presence Leveraging Extensions
or SIMPLE protocol 88. It is contemplated that the interface
protocols 80-88 are plug-ins that can interface directly with
corresponding servers in the enterprise network 20, which will be
further described below.
[0053] For the purposes of this disclosure, SIP 80 will be
utilized, although it is appreciated that the system 10 can operate
using the above disclosed or additional protocols. As known by
those of ordinary skill in the art, SIP is the IETF (Internet
Engineering Task Force) standard for multimedia session management,
and more specifically is an application-layer control protocol for
establishing, maintaining, modifying and terminating multimedia
sessions between two or more endpoints. As further known by those
of ordinary skill in the art, the SIP protocol 80 includes two
interfaces for signaling: SIP-Trunk (hereinafter referred to as
"SIP-T") and SIP-Line (hereinafter referred to as "SIP-L").
Specifically, the SIP-T interface is utilized when the endpoint is
a non-specific entity or not registered (i.e., when communicating
between two network entities). In contrast, the SIP-L interface is
utilized when the endpoint is registered (i.e., when dialing to a
specific extension). SIP is defined in J. Rosenberg et al., "RFC
3261--Session Initiation Protocol" (June 2002), the contents of
which are herein incorporated by reference. Other procotols,
extensions, and standards related to SIP may be implemented and
referenced, as appropriate. For example, Session Description
Protocol (SDP), as described herein, is defined in RFC 3264, and is
herein incorporated by reference.
[0054] The specific operation of the system 10 utilizing SIP 80
will be described in further detail below.
[0055] The SMP 18 also includes a plurality of enablers, among
other things, a VoIP enabler 90, a Fixed Mobile Convergence or FMC
enabler 92, a conference services enabler 94, a presence enabler 96
and an Instant Messaging or IM enabler 98. Each of the enablers
90-98 are used by corresponding services in the services layer 36
that combine one or more of the enablers. Each of the applications
in the application layer 38 is then combined with one or more of
the services to perform the desired application. For example, a
phone call service may use the VoIP or PBX enabler, and an
emergency response application may use the phone call service, an
Instant Messenger service, a video call service, and email service
and/or a conference service.
[0056] The application layer 38 may include a conference services
application 63 that, together with the conference services enabler
94, enables multiple communication devices (including desk
telephones and personal computers) to participate in a conference
call through use of a centralized conference server 55. As seen in
FIG. 5, the conference server 55 is provided in the enterprise
network 20 and is in communication with the conference services
enabler 94 preferably through the SIP protocol 80, although it is
recognized that additional protocols that control media separate
from data may be appropriate, such as the Web Services protocol 82
or the CTI protocol 86. As will be described in further detail
below, the conference call server 55 is configured for directing
media and data streams to and from one or more communication
devices (i.e., mobile devices 11, telephones 17, and computers
15).
[0057] Reference is now made to FIG. 6, which shows, in block
diagram form, an example PTT system, generally designated 110, for
implementing a push-to-talk (PTT) procedure 140 in accordance with
example embodiments. As shown, the PTT system 110 includes a PTT
server device 112 in communication with a number of PTT client
devices 114, illustrated as one PTT originator 116 and a plurality
of PTT receivers 118, 120, 122. The client devices 114 may
collectively form a PTT group. The PTT receivers 118, 120, 122 may
also sometimes be referred to as terminating devices.
[0058] The server device 112 includes a controller and a memory for
storage of, among other items, the media information of client
devices 114 which subscribe to a push-to-talk group. The server
device 112 includes a communications module or submodule for
communicating with other devices. The server device 112 may for
example be part of the call control server or SMP 18 (FIGS. 1-5).
The server device 112 may further be part of the enterprise or
business system 20 (FIG. 1). The server device 112 may include or
be coupled to the media server 76 (FIG. 4), wherein the server
device 112 controls the media handling of the media server 76.
[0059] Although the client devices 114 are illustrated as handheld
mobile communication devices (such as a smart phone, cellular
phone, soft phone, dual-mode phone, etc.), the client devices may
be any device configured with the functionality described herein,
and may for example include computer devices, relays, proxies,
gateways and any appropriate User Agents (as defined in SIP).
[0060] Reference is now to FIG. 7, which shows a subscription
procedure between the server device 112 and a client device 114.
Generally, the PTT system 110 provides a subscription-based
communications wherein certain information, including media
information, may be communicated between the client devices 114 and
the server device 112 prior to initiation of the actual PTT session
(also referred to as PTT call). Some communications within the PTT
system 110 implement the SUBSCRIBE and NOTIFY requests, which are
defined in A. B. Roach, "RFC 3265-Session Initiation Protocol
(SIP)-Specific Event Notification" (June 2002), the contents of
which are herein incorporated by reference.
[0061] In some conventional systems, a PTT session is implemented
by using INVITE to set a pre-established (or early) session mode.
However, such conventional systems using INVITE are limited to the
basic request/response functionality provided by INVITE. It is
recognized herein that the SIP SUBSCRIBE method and related
commands may provide further and additional functionality and
flexibility in implementation, as can be appreciated in view of the
description below.
[0062] Referring still to FIG. 7, a summary of the subscription
procedure 130 will now be described, which occurs prior to the PTT
call. At step 132, the client device 114 sends a SUBSCRIBE request
to the server device 112, including information regarding the
push-to-talk group number of the device and the port number of the
particular mobile device 114 that is used to receive subsequent
message, as well as for receiving a future PTT session. At step
134, the server device 112 provides a 200-OK message (accepting the
subscription request). The server device 112 may also reject the
subscription request (and/or the subscription request may fail),
for example using the 4xx or 5xx family of responses. At step 136,
the server device 112 sends a NOTIFY request to the client device
114, with media information including a port number of the media
server 176 (FIG. 4) for future PTT sessions originating from the
particular client device 114. At step 138, the client device 114
accepts the NOTIFY message by using 200-OK response. Generally, all
client devices 114 which are to form part of the PTT group would
implement the subscription procedure 130. The server device 112 is
therefore informed of the port information of each subscribing
client device 114, while each client device is informed of the port
information of the media server 176.
[0063] Referring now to FIG. 6, a summary of the PTT procedure 140
will now be described. Generally, the PTT procedure 140 is used to
establish a PTT call or session from the PTT originator 116 to the
PTT receivers 118, 120, 122. The PTT procedure 140 typically occurs
after the subscription procedure 130 (FIG. 7), with the media
parameters already communicated. At step 142, the PTT originator
116 sends another SUBSCRIBE request (indicated as "RE-SUSCRIBE" for
convenience) to the server device 112. At step 144, the server
device 112 sends NOTIFY requests to the PTT receivers 118, 120,
122. As will be described in detail below, the NOTIFY request
includes an indication of a new "active" state. At step 146, the
PTT receivers 118, 120, 122 respond with a 200-OK message if a PTT
call is acceptable to be received. A busy message such as 486-Busy
may be sent as a response if the particular PTT receiver 118, 120,
122 is busy or not accepting the PTT call. Each PTT receiver 118,
120, 122 which indicated 200-OK further opens its allocated port
for receiving media from the media server 76 (FIG. 4), for example
Real-Time Transport Protocol (RTP) media, as could be implemented
by those skilled in the art. At step 148, the server device 112
sends a 200-OK for the re-subscription message if at least one of
the PTT-receivers 118, 120, 122 is not busy. The media server 76
may thereafter open its media port for receiving or listening to
media from the PTT originator 116. The PTT originator 116
thereafter starts a media session (e.g. an RTP media session, as
could be implemented by those skilled in the art) to the port of
the media server 76, with media information previously received in
the NOTIFY step 136 (FIG. 7).
[0064] Detailed example implementations of the subscription
procedure 130 and PTT procedure 140 will now be described, with
reference to FIG. 8, which shows a general or generic example
message template 160 for the SUBSCRIBE and NOTIFY requests. As
shown, the message template includes a request 162, request headers
164 and associated body, and a SDP body (if present) 166. As shown,
the request 162 may be either a SUBSCRIBE request 168 or a NOTIFY
request 170, depending on the particular application and
implementation.
[0065] The request headers 164 include headers relating to the PTT
session information (the SUBSCRIBE or NOTIFY body is not shown here
as it is context dependent). The configuration of the particular
headers is dependent on the type of message being sent. The request
headers 164 include Max-Forwards, To, From, Call-ID, CSeq, Contact,
Event, Accept, Push-To-Talk-Group, Expires, Content-Type, and
Content-Length. Regarding the "Event:" header 172, RFC 3265 permits
the creation and use of "Event packages" which includes the
creation of templates, event package responsibilities, parameters,
and associated syntax and semantics for the headers 164. Thus, in
this particular example a "push-to-talk" event package is provided,
and indicated as "Event: push-to-talk" 172 (as shown). The headers
164 may further contain a "Push-To-Talk-Group:" 174 and associated
"state=", which are created in the particular Event package. Note
that the INVITE does not typically contain or provide for such
Event packages.
[0066] The SDP body 166 includes parameters relating to session
description 176, time description 178, and media description 180.
These parameters are described in SIP. As can be appreciated, the
SDP body 166 would not be present in some of the requests, such as
in the RE-SUSCRIBE 142 and NOTIFY 144 messages (FIG. 6). Further,
the media description 180 would not be present in some of the
requests, for example when media information is already provisioned
in advance of a PTT session. The SDP body 166 as shown may include
parameters indicated by an asterisk (*) which are considered
optional as defined by SIP (not to be confused with parameters
which are optional in the present PTT system 110).
[0067] The subscription procedure 130 (FIG. 7) and PTT procedure
140 (FIG. 6) will now be described in greater detail. Reference is
now made to FIG. 9, which shows an example message 207 for
implementing the SUBSCRIBE step 132 (FIG. 7) in detail. As shown,
the message 207 indicates in the header "Event: push-to-talk" 203.
The message 207 also contains the "Push-To-Talk-Group" header 204
that indicates a specific PTT group-identifier (ID) which the
client device 114 is subscribing to. The message 207 also includes
in the body of the "Push-To-Talk-Group" header 204 a current
"state" 206 of the client device. For example, the state 206 may be
"idle" while available to receive a PTT call, or "active" while
wishes to initiate a PTT call. In the present message 207 for
subscribing to a PTT group, the state 206 is set to "idle", as
shown. The SUBSCRIBE message 100 also includes an "Expires:" header
208, which includes in the body the requested expiry information of
the particular subscription to the PTT group. The expiry
information is stored by the server device 112 and generally
indicates when the subscription to the PTT group is expired, and
may be refreshed by subsequent SUBSCRIBE messages.
[0068] The message 207 further includes a SDP body 210, which
contains media information 212 including port information of the
client device 114. In the example shown, the media information 212
is "SDP m-header port number 50000", which is the port number that
will be used by the client device 114 for receiving the incoming
media when a PTT call is received by the client device 114. For
example, port information may include Internet Protocol (IP) port,
codec, etc. In some example embodiments, the media information 212
is sent from the server device 112 to the media server 76 for
storage by the media server 76 to implement a future media session
with the client device 114. In other example embodiments, the media
information 212 is stored by the server device 112 and passed on to
the media server 76 when the media session starts.
[0069] The server device 114 can authenticate this request if
needed and either accept or reject the subscription. If the
subscription is accepted the server device 112 will send 200-OK
response 134 (FIG. 7) to indicate the successful status of the
subscription.
[0070] The client device 114 can re-subscribe by sending another
SUBSCRIBE message to the server device 112 if it wishes update the
subscription, for example to modify or update SDP capabilities,
expiry, state or ID of the Push-To-Talk-Group.
[0071] Reference is now made to FIG. 10, which shows an example
message 220 for implementing the NOTIFY step 136 (FIG. 7) in
detail. As shown, the NOTIFY message 220 includes the same Call-ID,
an incremented CSeq (727 versus 726 as in the SUBSCRIBE message
207), and the same From and To headers. Thus, the NOTIFY message
220 includes some of the same headers 226 as the SUBSCRIBE message
207 (FIG. 9). As shown, the NOTIFY message 220 also includes the
same event package, including the header "Event package:
push-to-talk" 228 and the header for "Push-To-Talk-Group" 230 as in
the original SUBSCRIBE message 207. Once the server device 114 has
accepted the subscription of the client device 114 to the
particular PTT group, the server device 112 provides to the client
device 114 media information 222 of the media server 76. As shown,
the SDP body 224 includes the media information 222, including port
information of the media server 76 to the client device 114. The
client device 114 may store the media information 222 and use the
media information 222 to implement a future PTT session when the
client device 114 acts as a PTT-Originator 116 (FIG. 6). The
specific server device 112 and media server 76 negotiations would
be understood by those skilled in the art.
[0072] Referring still to FIG. 10, with regards to the Expires
header 232 (shown as "Expires: 2900"), the server 112 may reduce
the expiration value, and client device 114 must adhere to this new
expiration value. In other example embodiments, the server 112 may
reply with a SIP-Expires in the header of a 200 OK in response to
the SUBSCRIBE command 132.
[0073] In some example embodiments, the server device 112 upon
receiving of the SUBSCRIBE request (including the expiration value)
from client device 114 will start a timer for the present
subscription. Once the timer has expired the server device 112 will
notify the client device 112 about the terminated/terminating state
of the subscription by means of another NOTIFY request.
[0074] The client device 112 accepts the provisioning NOTIFY
message 220 request by responding with 200-OK 138 (FIG. 7).
[0075] In some embodiments, the server device 112 can periodically
send updated NOTIFY messages to the client device(s) 114, which may
for example include updated SDP information. Thus, the client
device 114 may be configured to check for the SDP body in the
NOTIFY messages.
[0076] Reference is now made to FIG. 11, which shows an example
SUBSCRIBE message 240 for implementing the RE-SUBSCRIBE step 142
(FIG. 6) in detail, for initiating the PTT call or session to the
PTT group. As shown, the SUBSCRIBE message 240 does not include an
SDP body, as the SDP information (including media information) was
previously provided in the previous SUBSCRIBE message 207 (FIG. 9).
As shown, in the "Push-To-Talk Group" header 242, the "state" 244
is set to "active". This indicates that the particular client
device 114 is initiating a PTT session to the PTT receivers 118,
120, 122 in the PTT group and is acting as the PTT originator 116
(FIG. 6). As can be appreciated, using the SUBSCRIBE message 240 to
initiate the PTT session would include additional information (such
as the event package) when compared to a conventional INVITE
message.
[0077] After the SUBSCRIBE message 240 has been sent to the server
device 112, the PTT-originator 116 can start the media session
(such as an RTP-session) to the media information 222, including
the media port, that was previously provided in the NOTIFY message
220 (FIG. 10).
[0078] The server device 112 checks whether the current state of
the PTT group is "idle" and that there is no "active" PTT session.
The server device 112 also verifies whether the PTT originator 116
has permission to initiate the PTT session (the floor control
functionality of the server device 112 would be understood by those
skilled in the art), for example if the "expiry" for the particular
subscription has expired. If the request by the PTT originator 116
is acceptable, the server device 112 will mark the PTT group as
"active" and follow to the next NOTIFY step 144. Otherwise the
request will be rejected by the server device 112 sending to the
PTT originator 116 one of the SIP-reject codes (e.g. 486 Busy
Here).
[0079] Reference is now made to FIG. 12, which shows an example
NOTIFY message 260 for implementing the NOTIFY step 144 (FIG. 6).
The server device 112 will send the NOTIFY message 260 to all PTT
receivers 118, 120, 122 of the PTT group (FIG. 6). The NOTIFY
message 260, as shown, indicates the "state" 262 is set to
"active". The NOTIFY message 260 is typically sent to those PTT
receivers 118, 120, 122 which had previously subscribed to the PTT
group (using the subscription procedure 130, FIG. 7) and whose
particular subscriptions have not expired, as determined by the
server device 112.
[0080] If a PTT-Receiver 118, 120, 122 is not willing to accept the
PTT call, the PTT-Receiver shall be configured to not receive any
RTP session and reject the NOTIFY message 260 request, for example
by responding with 486 Busy Here (or 480 Temporary Unavailable)
SIP-responses. Otherwise, the PTT-Receiver 118, 120, 122 will open
the port (e.g., "listen") which it has allocated for the media
session in step 132 (FIG. 7) for receiving the RTP-media. The
PTT-Receiver 118, 120, 122 thereafter starts playing (e.g.
outputting to a speaker, not shown) the RTP-media received on the
port.
[0081] Once any one of the PTT receivers 118, 120, 122 sends a 200
OK response to the NOTIFY message 260 request, the server device
112 will send 200 OK (or 202 Accepted) 148 response to the
SUBSCRIBE message 240 request (FIG. 11)
[0082] It can be appreciated that another client device 114 (such
as one of the PTT receivers 118, 120, 122) would not be able to
start another PTT session while the current state of the group is
"active".
[0083] Referring to FIG. 6, in order to terminate a PTT session,
the PTT originator 116 sends a new RE-SUBSCRIBE request (using a
SUBSCRIBE message similar to SUBSCRIBE message 240, FIG. 11), in
this case with the "state" indicated as "idle". The server device
112 will terminate the sessions with the PTT receivers 118, 120,
122 by sending terminating NOTIFY requests (similar to the NOTIFY
message 260, FIG. 12) with the "state" indicated as "idle" to all
PTT receivers 118, 120, 122. Once the request to terminate the
session by the PTT originator 116 is received, the PTT session is
considered as terminated and the server device 112 must reset
states of the all group members to "idle" regardless of responses
received for the terminating NOTIFY requests to the PTT receivers
118, 120, 122.
[0084] Referring to FIG. 6, in order for a client device 112 to
unsubscribe from the push-to-talk service (or a specific PTT
group), the client device 112 must follow an un-subscription
procedure, for example as described in RFC 3265, as would be
understood by those skilled in the art.
[0085] In some example embodiments, the client devices may be
designated as dedicated PTT originators or dedicated PTT receivers.
Thus, in some of the provisioning message requests, certain media
information including media port information would not be included,
as such information would not be used by the dedicated PTT
originators or dedicated PTT receiver, thereby reducing the size of
the required message content.
[0086] Certain adaptations and modifications of the described
embodiments can be made. Therefore, the above discussed embodiments
are considered to be illustrative and not restrictive.
* * * * *