Patent Publication Number: US-2007105578-A1

Title: Method and system for providing a push-to-talk communication session using a control endpoint

Description:
BACKGROUND OF THE INVENTION  
      Many public and private groups, such as security and safety personnel (e.g., police, fire fighters and ambulance drivers) use various communication networks of differing technologies and types for communication. Many networks utilize land mobile radios communicating through push-to-talk technologies. However, communications among different endpoints of different networks such as endpoints of different police, fire or other security networks may be difficult. Collaboration between the different agencies and networks tends to be ad hoc and inefficient. When achieved, it often involves laborious manual intervention. Organizations working towards interoperability solutions include Raytheon JPS Communications, IP Blue, Twisted Pair, M/A-COM, Motorola and Cisco Systems.  
      In addition, many networks of public and private groups, such as security and safety personnel, utilize push-to-talk technology to enable communications among members of a particular group. Groups members may communicate using push-to-talk endpoints, such as land mobile radios. These endpoints are typically half duplex endpoints such that they cannot support both outgoing and incoming communications at one time.  
     SUMMARY OF THE INVENTION  
      The present invention on provides a method and system for providing a push-to-talk communication session using a control endpoint that substantially eliminates or reduces at least some of the disadvantages and problems associated with previous methods and systems.  
      In accordance with a particular embodiment, a method for providing a push-to-talk communication session includes facilitating a push-to-talk communication session among a full duplex endpoint supporting simultaneous two-way communication and a plurality of half duplex endpoints. Communications are received from and transmitted to the full duplex endpoint along a two-way communications path. The method includes blocking communications received from the full duplex endpoint while one of the plurality of half duplex endpoints has floor control in the communication session and receiving from the full duplex endpoint in the two-way communications path a floor control signal comprising a request to transmit communications in the communication session. The method includes, in response to receiving the floor control signal, providing floor control to the full duplex endpoint and transmitting to the plurality of half duplex endpoints communications received from the full duplex endpoint.  
      In accordance with another embodiment, a method for providing a push-to-talk communication session using a control endpoint includes facilitating a push-to-talk communication session among a full duplex endpoint supporting simultaneous two-way communication and a plurality of half duplex endpoints. Communications are received from and transmitted to the full duplex endpoint along a two-way communications path. The method includes blocking communications received from the full duplex endpoint while one of the plurality of half duplex endpoints has floor control in the communication session and receiving, from a control endpoint separate from the full duplex endpoint, a floor control signal comprising a request to transmit communications in the communication session. The method includes, in response to receiving the floor control signal, providing floor control to the full duplex endpoint and transmitting to the plurality of half duplex endpoints communications received from the full duplex endpoint.  
      In accordance with another embodiment, a method for providing a push-to-talk proxy media service includes receiving a plurality of monitored push-to-talk communication streams over a high bandwidth connection and mixing the plurality of monitored push-to-talk communication streams into a mixed communication stream. The method also includes transmitting the mixed communication stream to a user endpoint over a low bandwidth connection.  
      Technical advantages of particular embodiments include the ability of a user of a full duplex endpoint to communicate in a push-to-talk communication session with half duplex endpoints. Moreover, in some cases the user may utilize an endpoint different from the full duplex endpoint to control the floor in a push-to-talk communication session. Moreover, particular embodiments provide a proxy media service to enable a user to monitor a plurality of communication sessions, such as a plurality of PTT communication sessions, over a connection with an interoperability system through a low bandwidth network, such as a WAN. Thus, the ability to monitor many communication sessions is provided to users despite the lack of high bandwidth access to the interoperability system. This may provide users with the ability to monitor such communication sessions from home, for example, over a DSL or other connection instead of having to monitor from a company&#39;s or other organization&#39;s high bandwidth LAN.  
      Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some or none of the enumerated advantages.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a more complete understanding of the present invention and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:  
       FIG. 1  illustrates a communication system with various communication networks and an interoperability system, in accordance with a particular embodiment;  
       FIG. 2  illustrates an example interoperability system, in accordance with a particular embodiment;  
       FIG. 3  illustrates an example system for providing a push-to-talk communication session among a full duplex endpoint and a plurality of half duplex endpoints, in accordance with a particular embodiment;  
       FIG. 4A  illustrates an example system for providing a push-to-talk communication session using a control endpoint, in accordance with a particular embodiment;  
       FIG. 4B  illustrates another example system for providing a push-to-talk communication session using a control endpoint, in accordance with a particular embodiment;  
       FIG. 5  illustrates an example system for providing a push-to-talk proxy media service, in accordance with a particular embodiment;  
       FIG. 6  illustrates a method for providing a push-to-talk communication session, in accordance with a particular embodiment;  
       FIG. 7  illustrates a method for providing a push-to-talk communication session using a control endpoint, in accordance with a particular embodiment; and  
       FIG. 8  illustrates a method for providing a push-to-talk proxy media service, in accordance with a particular embodiment.  
    
    
     DETAILED DESCRIPTION  
       FIG. 1  illustrates a communication system  10 , in accordance with a particular embodiment. Communication system  10  includes communication networks  24   a - 24   e , interoperability system (IS)  20  and endpoints  22   a - 22   c . IS  20  is able to facilitate interoperable communication sessions between and among various communication devices, such as endpoints of communication networks  24  and endpoints  22 . IS  20  uses a systems approach to offer a framework based on IP protocols and services to immediately achieve secure voice, video and other data interoperability among communication endpoints and networks utilizing different technologies.  
      Particular embodiments provide a user of a full duplex endpoint to communicate in a communication session with push-to-talk (PTT) half duplex endpoints. In general, a full duplex endpoint is capable of sending and receiving communications at the same time (e.g., along a 2-way communications path). A half duplex endpoint can only send or receive communications at the same time (e.g., it cannot support simultaneous 2-way communication). Thus, to effectively communicate with a half duplex endpoint, only one party can talk at any one time as only one channel is available. Therefore, to speak in a PTT manner with another half-duplex PTT endpoint, a user must “control the floor” by pressing and/or otherwise activating a PTT button which sends a signal to other PTT endpoint(s) on the channel or frequency to let them know that the user has control of the floor. This is in contrast to full duplex endpoints, such as typical telephones which can both send and receive communications at once because outgoing and incoming communications are sent along separate channels or, in other words, along a 2-way communications path.  
      Particular embodiments facilitate interoperable PTT communications among PTT half-duplex endpoints and a full duplex endpoint through, for example, an interoperability system. The system provides a user of the full duplex endpoint with various methods for controlling the floor in order to communicate with the half duplex endpoints. In some embodiments a DTMF or other signal may be communicated through the main communications path through which normal media communications are carried. In some cases a separate control endpoint may be used for the floor control signal. When the full duplex endpoint does not have floor control in a PTT session, the system may block any communications from the full duplex endpoint to allow the half duplex endpoints to communicate in the session. Thus, PTT functionality is provided to full duplex endpoints for interoperable communications with half duplex PTT endpoints of other communication networks.  
      Moreover, particular embodiments provide a proxy media service to enable a user to monitor a plurality of communication sessions, such as a plurality of PTT communication sessions, over a connection with an interoperability system through a low bandwidth network, such as a WAN. A proxy media system may mix streams from the plurality of communication sessions for effective communication to the user over the low bandwidth network. Thus, the ability to monitor many communication sessions is provided to users despite the lack of high bandwidth access to the interoperability system. This may provide users with the ability to monitor such communication sessions from home, for example, over a DSL or other connection instead of having to monitor from a company&#39;s or other organization&#39;s high bandwidth LAN.  
      In the illustrated embodiment, communication networks  24   a  and  24   d  comprise radio networks (RNs), communication network  24   b  comprises a local area network (LAN), communication network  24   c  comprises a PSTN and communication network  24   e  comprises an IP network. It should be understood, however, that communication system  10  may comprise any number of IP or non-IP communication networks of any wireless or wireline form capable of communicating audio and/or video telecommunication signals, data, and/or messages, including signals, data or messages. Communication networks  24   a - 24   e  may include any number and combination of segments, nodes and endpoints to enable communication among network devices and components. Communication networks  24   a - 24   e  may be distributed locally or across multiple cities and geographic regions. Nodes may include any combination of network components, gatekeepers, call managers, conference bridges, routers, hubs, switches, gateways, base stations, endpoints or other hardware, software or embedded logic implementing any number of communication protocols that allow for the exchange of data in communication system  10 . Segments  30 , which may comprise any suitable wireless or wireline communication links, including one or more communication networks (e.g., WANs) as appropriate, couple various networks with each other and with endpoints  22  and IS  20 . In particular embodiments, segments may include gateways for facilitating communication between various networks, such as an LMR gateway between radio network  24   a  and IP network  24   e.    
      In some cases, users of endpoints of one of communication networks  24   a - 24   e  may communicate with endpoints of another of communication networks  24   a - 24   e  through facilitation provided by IS  20 . A radio network, such as radio network  24   a  or  24   d , may support communication among portable mobile station endpoints, such as land mobile radios (LMRs), using any suitable communication methods or features, such as cellular and push-to-talk (PTT). Communication networks  24   a - 24   e  may comprise networks of particular groups or agencies (e.g., a municipality&#39;s police department network or a company&#39;s network), whether operational with respect to a particular area or otherwise.  
      IS  20  enables, facilitates and/or provides for interoperable communication among communication endpoints and devices, such as LMRs, cellular phones, IP phones, PCs, PDAs, PSTN phones, video monitors, cameras and sensors of one or more communication networks (e.g., communication networks  24   a - 24   e ) using Internet Protocol. Such endpoints may comprise IP or non-IP-enabled endpoints. In particular embodiments, IS  20  may control gateways (for example, of segments  30 ) in order to map radio frequencies of particular mobile radio endpoints to IP addresses for communication to other types of radio endpoints or IP devices. For example, a particular gateway may be able to receive communications from various types of endpoints (e.g., on various types of communication networks) and may convert such communications for transmission to other types of endpoints. IS  20 &#39;s control of the gateway may control the various endpoints and/or networks that receive particular communications, depending on system functionality and configuration as further discussed below. As indicated, such control may include the mapping of communications and endpoints to IP addresses for interoperable communication. In some embodiments, IS  20  may host audio conferences that bridge communications received from endpoints. As indicated above, communication system  10  (including IS  20 ) may include any suitable number or type of gateways (e.g., LMR and PSTN gateways), servers (e.g., multipoint conference servers), switches, routers, firewalls, access points, processors, memory or other hardware, software or encoded logic to provide functionality described herein. IS  20  is coupled to communication networks  24   a - 24   d  and endpoints  22  through IP network  24   e , which may comprise any suitable IP network.  
      As indicated above, IS  20  uses IP to enable communication among endpoints of various networks. The manner in which IS  20  facilitates communications among endpoints may vary according to location and system or operational needs. For example, IS  20  may communicate with endpoints using multicast IP addresses assigned to an endpoint of a communication network, a group of endpoints of a communication network or one or more endpoints of multiple communication networks or alternatively using a peer to peer dialed connection or a nailed dialed connection. A group of endpoints may be combined into a virtual talk group for communication using a particular IP address. As an example, the virtual talk group may be assigned a multicast IP address through which users of various embodiments may communicate on the talk group. The use of multicast IP addresses allows IS  20  to facilitate communications among communication devices and endpoints of various communication networks to provide audio, data, video and control network interoperability. As an additional example, in some cases multicast streams (e.g., utilizing multicast IP addresses) may be used. In some cases nailed dialed connections, such as those using SIP protocol, may be used for communication among endpoints and with IS  20 . Various embodiments may combine communication methods to facilitate communication among endpoints. For example, in some cases certain endpoints of a virtual talk group may participate in the talk group through a multicast IP address while other endpoints may utilize a nailed SIP connection. IS  20  may control this participation, such as by controlling gateways, multipoint conferences and the mapping of communications to IP addresses.  
      IS  20  may be utilized and implemented in any number of market segments, such as enterprise safety and security (e.g., loss prevention), transportation, retail, public safety and federal agencies in order to provide radio and non-radio network interoperability within and between such market segments. As indicated above, such network interoperability includes the interoperability of push-to-talk voice technology within various networks and the interoperability between push-to-talk and full duplex dialed connections.  
      It will be recognized by those of ordinary skill in the art that endpoints  22  and IS  20  may be any combination of hardware, software, and/or encoded logic that provides communication services to a user. In the illustrated embodiment, endpoints  22  comprise a PC (endpoint  22   a ), a PDA (endpoint  22   b ) and an IP phone  22   c ). However, in other embodiments, endpoints  22  may include a telephone, a personal computer (PC), a video monitor, a camera, an IP phone, a cell phone, a land mobile radio (LMR), a personal digital assistant (PDA), a command center or any other communication hardware, software and/or encoded logic that supports the communication of audio, video or other data, using packets of media (or frames) or otherwise, through communication system  10 . Endpoints  22  as well as endpoints and components of communication networks  24  may be capable of communicating using any particular type of technology, such as cellular, IP, PSTN, CDMA, GSM, TDMA and satellite. Endpoints  22  and IS  20  may also include unattended or automated systems, gateways, other intermediate components or other devices that can establish media sessions.  
      Although the illustrated embodiment includes five communication networks  24   a - 24   e , the term “communication network” should be interpreted as generally defining any network capable of transmitting audio and/or video telecommunication signals, data, and/or messages, including signals, data or messages. Any one of networks  24   a - 24   e  may be implemented as a local area network (LAN), wide area network (WAN), cellular network, global distributed network such as the Internet, Intranet, Extranet, PSTN, LMR network, CDMA network, GSM network, TDMA network, satellite network or any other form of wireless or wireline communication network.  
      Communications over communication networks  24   a - 24   e  may use any suitable communication protocol. In a particular embodiment, some communication networks may employ voice communication protocols that allow for the addressing or identification of endpoints, nodes, and/or other components coupled to the communication network. For example, using Internet protocol (IP), each of the components coupled together by, for example, communication network  24   b  in communication system  10  may be identified in information directed using IP addresses. In this manner, network  24   b  may support any form and/or combination of point-to-point, multicast, unicast, or other techniques for exchanging media packets among components in communication system  10 . Any network components capable of exchanging audio, video, or other data are included within the scope of the present invention.  
      Since IP networks share a common method of transmitting data, telecommunication signals may be transmitted between telephony devices located on different, but interconnected, IP networks. In addition to being coupled to other IP networks, communication network  24   b  may also be coupled to non-IP telecommunication networks, for example through the use of interfaces or components, including gateways. In the illustrated embodiment, communication network  24   b  may be coupled with PSTN  24   c  through a gateway. In some embodiments the gateway may be a part of IS  20  or network  24   e . PSTN  24   c  includes switching stations, central offices, mobile telephone switching offices, pager switching offices, remote terminals, and other related telecommunications equipment that are located throughout the world. IP networks transmit data (including voice and video data) by placing the data in packets and sending each packet individually to the selected destination, along one or more communication paths. Unlike a circuit-switched network (like PSTN  24   c ), a dedicated circuit is not required for the duration of a call or fax transmission over IP networks.  
      Technology that allows telecommunications to be transmitted over an IP network may comprise Voice over IP (VoIP), or simply Voice over Packet (VoP). In the illustrated embodiment, one or more of endpoints  22 , and endpoints and components of communication networks  24  may be IP telephony devices capable of participating in IM, video, and other multimedia communication sessions. IP telephony devices have the ability of encapsulating a user&#39;s voice (or other input) into IP packets so that the voice can be transmitted over a communication network. IP telephony devices may include telephones, fax machines, computers running telephony software, nodes, gateways, wired or wireless devices, hand held PDAs, or any other device capable of performing telephony functions over an IP network.  
      In particular embodiments, communication system  10  may receive and transmit data in a session initiation protocol (SIP) environment. SIP is an application-layer control protocol that includes primitives for establishing, modifying and terminating communication sessions. SIP works independently of underlying transport protocols and without dependency on the type of session that is being established. SIP also transparently supports name mapping and redirection services, which support personal mobility.  
      Although  FIG. 1  illustrates a particular number and configuration of endpoints, IS and communication networks, communication system  10  contemplates any number or arrangement of such components for communicating media.  
       FIG. 2  illustrates interoperability system (IS)  50 , in accordance with a particular embodiment. IS  50  may be similar to and provide the same functionality as IS  20  of  FIG. 1 . In the illustrated embodiment, IS  50  includes interface  51 , gateways  52 , operations management application (OMA)  54 , multipoint conference system (MCS)  56 , policy engine  58 , authentication and security system  60 , call manager  62 , processor  64  and memory module  66 . IS  50  is coupled to a PC endpoint  70  that may be used to access, configure and control various functionality provided by IS  50 . PC endpoint  70  may run a client application for such access, configuration and control. The client application may enable a user of endpoint  70  to receive and monitor communications from various endpoints and virtual talk groups. In particular embodiments, other types of endpoints may be utilized to access, configure and control IS  50 , such as IP phones, PDAs and mobile devices. IS  50  may be coupled to such endpoints (including PC endpoint  70 ) through one or more communication networks.  
      Interface  51  is used in the communication of audio, video, signaling and other data between IS  50  and other network components. For example, interface  51  may receive communications from endpoints such as endpoints of communication networks  24 , endpoints  22  and endpoint  70 . The communication may take place over IP networks thereby negating the need for dedicated wiring between the endpoints and the IS.  
      Gateways  52  may include any suitable gateways to provide network interoperability and back-end legacy application integration, such as LMR gateways, PSTN gateways and application gateways. Gateways  52  provide mapping between IP services and the interoperable networks, such as LMR network  24   a  of  FIG. 1 . In some cases gateways  52  may not be located within an IS but may be distributed throughout a communication system for enabling communications among various communication networks.  
      Operations management application (OMA)  54  includes functionality for configuration, management and control of IS  50 , including conference and collaboration management, and may be accessed by a user via, for example, PC endpoint  70 . In particular embodiments, OMA  54  may enable a user, such as dispatch personnel or administrators or a mobile user (e.g., a first responder mobile user) accessing IS  50  via a mobile endpoint, the ability to configure, manage and participate in one or more virtual talk groups and ad hoc conferences simultaneously. In particular embodiments, OMA  54  may be accessed through a web interface, functioning for example as a soft phone for radios. A screen display may be controlled using a mouse, keypad, touch screen, voice commands or any other suitable interface. OMA  54  screens may include any number of functional controls to provide interoperable communications. OMA  54  may authenticate a user and obtain user configuration information upon a user accessing the OMA. OMA  54  may monitor and provide communication ability for any number of channels at one time to provide the ability for an OMA user to communicate on and control multiple virtual talk groups at once.  
      Multipoint conference system (MCS)  56  provides collaboration and conference services for multiple endpoints of one or more networks. For example, users of multiple endpoints (such as LMRs of different networks (e.g., networks of different agencies or groups) and different types of endpoints of different networks) may be bridged together through MCS  56  to provide virtual talk group communications. MCS  56  may include any suitable number or type of conference bridges, ports, digital signal processors or other components to facilitate communications discussed herein.  
      Policy engine  58  includes policies for undertaking various operations and functionality upon the occurrence of various events to provide dynamic incident management. These policies may include both pre-determined and ad hoc policies. For example, upon the occurrence of a particular incident, the incident may include a unique identifier and may have basic incident attributes such as time of creation, name of user creating and status. A pre-determined policy may then be executed by an incident manager or dispatch personnel as action for the specific incident. In particular embodiments, policy engine may receive inputs from alarms and sensors to setup device agnostic communications interoperability and one-way video and data collaboration and to trigger additional events such as pagers, e-mails, notifications, dial-outs, recording and information escalation.  
      Authentication and security system  60  manages access, configuration and control privileges for users of IS  50  and those participating in interoperable communications. For example, different users may have different privileges assigned for interoperable communications. Some users may only have transmit or listen privileges with respect to one or more particular talk groups, while other users may have the ability to communicate in all talk groups or setup and configure various talk groups. User privileges may change dynamically upon the occurrence of particular events.  
      Call manager  62  maintains information regarding various users, such as users of IP networks for which interoperable communications are provided by IS  50 . This facilitates in the extension of PTT to IP networks and in the provision of voice and data interoperability across radio and non-radio networks. In particular embodiments, call manager  62  may maintain a listing, table, or other organization of information about users. The information may include a name or other identifier and contact information such as phone numbers and email addresses for the users. In particular embodiments call manager  62  may represent any appropriate combination of hardware, software and/or encoded logic distributed throughout a communication network coupled with IS.  
      Processor  64  may be a microprocessor, controller, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other IS components such as OMA  54 , IS  50  functionality. Such functionality may include providing various features discussed herein to a user, such as a user of an endpoint accessing IS  50  through OMA  54 . Such features may include providing to the user endpoint location information of communicating endpoints of a plurality of monitored endpoints and/or virtual talk groups, enabling the user to listen to and/or participate in communications involving endpoints and/or virtual talk groups of a particular geographic area, presenting communications of endpoints of scene-related virtual talk groups according to preconfigured or received instructions and controlling various gateways and other network components to facilitate interoperable communications among various endpoints.  
      Memory module  66  may be any form of volatile or non-volatile memory including, without limitation, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. Memory module  66  may store any suitable data or information, including software and encoded logic, utilized by IS  50 . In particular embodiments, memory module  66  may include data for user management, talk-group management, resource pool management, privileges, backup configuration and information and/or timestamp and activity tracking.  
      IS  50  may also include any number of switches, routers, firewalls, mobile access routers, access points, wireless bridges and other components in order to accommodate particular operational desires and needs.  
      In particular embodiments such as in the LMR network interoperability context, IS  50  may, through one or more components discussed above or through other components, encode received audio with a standard audio codec, such as G.711 or G.729. Those audio samples may be packaged in standards-based real-time transport protocol (RTP) packets suitable for transport on an IP network. At this point, the communication element may be abstracted from the distinctive characteristics of each radio system. These audio packets can be sent across the network to other radio systems either individually (unicast) or as a group (multicast). The recipient of the audio packets may be a device capable of receiving and decoding the RTP stream, such as an IP telephone or PC with appropriate software. The IP network and IP-enabled devices can be used to allow users to monitor or transmit on a particular radio channel from a desk without issuing another radio.  
      As indicated above, IS  50  may facilitate communication among users of endpoints of various networks through virtual channels or talk groups. For example, a channel may comprise a unidirectional or bidirectional path for transmitting and/or receiving electrical or electromagnetic signals. This may comprise, for example, a conventional radio physical RF channel. A talk group in this context may be a subgroup of users (e.g., radio users) who share a common functional responsibility and typically coordinate actions amongst themselves without radio interface with other subgroups. For example, a municipality&#39;s police department network may include various talk groups of various users.  
      A virtual talk group (VTG) represents interoperability of a group of channels, for example, as an audio conference or meeting. A virtual talk group may include an associated virtual channel and an ID. Virtual channels may comprise an address, such as an IP address, associated with a virtual talk group through which users may access the virtual talk group and/or through which communications from VTG member-endpoints are bridged. Various types of virtual talk groups may be utilized in particular embodiments, such as a multicast address usable by all endpoints of the VTG, a VTG comprising multiple talk groups (e.g., multiple radio sources from different frequencies whose communications are mixed), a unicast group and a combination unicast and multicast group.  
      As an example, a particular virtual talk group may comprise a conference or meeting of the following: (1) a channel or other multicast path used by certain users of a police department&#39;s radio network, (2) a channel or other multicast path used by certain users of a fire department&#39;s radio network, (3) a channel or other multicast path used by certain users of a corporation&#39;s security radio network and (4) a plurality of users of IP-enabled endpoints such as IP phones, IP-enabled PDAs or PCs. An operator of IS  50  may configure the virtual talk group using any suitable interface, such as by dragging and dropping the included channels and IP endpoints into a single area representing the virtual talk group. MCS  56  may provide the functionality for the conference of the virtual talk group members. In particular embodiments, multiple talk groups may be patched together on a dynamic, as needed basis. In some cases a virtual talk group may not necessarily include communications through an IS but may instead include member endpoints whose communications are mapped to IP addresses at gateways (such as LMR gateways) controlled by an IS.  
      Any number of virtual talk groups may be configured to provide any suitable audio, data, video and control network interoperability. Virtual talk groups may be created using any suitable user/endpoint groups or channels based on location, organizational requirements, event requirements or any other suitable characteristic. An administrator or operator may configure channel details such as name, description, participants, multicast IP addresses, codec and latch options through, for example, OMA  54 .  
       FIG. 3  illustrates a system for providing a push-to-talk communication session, in accordance with a particular embodiment. The illustrated embodiment includes a full duplex endpoint  80  and a plurality of half-duplex endpoints  90  coupled to an IS  100 . It should be understood that  FIG. 3  is only a logical illustration, and endpoints  80  and  90  may be coupled to IS  100  through any number of communication networks, such as an IP network. For example, IS  100  may act as a node coupled to an IP network as illustrated with respect to IS  20  of  FIG. 1 . In some cases, communications between endpoints  80  and  90  may not travel through IS  100  but may travel through gateways and other network components controlled by an IS. In particular embodiments, endpoints  80  and  90   a - 90   c  may comprise endpoints of different communication networks or communicating on different frequencies, such as endpoints of different police departments, fire departments or other security agencies or groups, including various users of a private organization or company. Endpoints  80  and  90   a - 90   c  may typically communicate on their own communication networks or on separate frequencies. In this case communications between endpoints  80  and  90   a - 90   c  are facilitated by IS  100  (e.g., bridged through IS  100  in some cases) for interoperable communication with each other in a virtual talk group using Internet Protocol as generally described above with respect to  FIGS. 1 and 2 .  
      In the illustrated embodiment, endpoints  90   a  and  90   b  are part of communication network  95   a , and endpoint  90   c  is a part of communication network  95   b . Communication networks  95   a  and  95   b  may comprise, for example, land mobile radio networks of different agencies or groups. It should be understood that endpoints  80  and  90  may communicate with IS  100  through any of a variety of communication networks, such as one or more WANs, LANs, cellular networks, PSTNs, LMR networks, CDMA networks, GSM networks, TDMA networks or satellite networks. IS  100  may be similar to, and may provide similar functionality as, IS  50  discussed above. IS  100  may include the same or similar components as IS  50  and may also include a PTT floor control proxy system comprising any suitable processor or hardware, software or encoded logic to provide the functionality described herein.  
      Endpoint  80  may comprise a PSTN phone, cell phone or other suitable full duplex endpoint and may include various functionality provided by endpoint  70  described above, such as the ability to access, configure and control various functionality provided by an IS and the ability to run a client application for such access, configuration and control. In the illustrated embodiment, endpoint  80  includes a transmitter/receiver  82 , a user interface  84 , a processor  86  and a memory module  88 . Transmitter/receiver  82  transmits and receives communications such as audio, video, instant messaging and other data to and from other network components. User interface  84  provides a mechanism through which a user of endpoint  80  may operate the endpoint and communicate with other network devices. Interface  84  may comprise, for example, a microphone, a speaker, a keypad (e.g., for transmitting DTMF signals) or any other suitable interface. Instructions may be submitted through speech recognition, collection of keystrokes, soft key or otherwise.  
      Processor  86  may be a microprocessor, controller, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to perform endpoint functionality. Processor  86 , either alone or in conjunction with other endpoint components, provides endpoint functionality discussed herein. Memory module  88  may be any form of volatile or non-volatile memory including, without limitation, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component.  
      Endpoint  80  comprises an endpoint capable of communicating in a full duplex manner, such as a cellular phone. Thus, endpoint  80  may receive and transmit communications at the same time using, for example, separate communication channels for incoming and outgoing communications. Endpoints  90  comprise any suitable half-duplex devices, such as push-to-talk land mobile radios. Thus, endpoints  90  may only either transmit or receive communications at one time, as one communication channel is used for incoming and outgoing communications. As indicated above, particular embodiments provide a user of a full duplex endpoint, such as endpoint  80 , with the ability to communicate through PTT technology with one or more users of half-duplex endpoints, such as endpoints  90 .  
      As an example, a user of a full duplex endpoint, such as endpoint  80 , calls into IS  100  in order to participate in a virtual talk group of users of half-duplex, push-to-talk land mobile radios, such as endpoints  90 . A multipoint conference system of the IS may bridge together transmissions from an endpoint  80  or  90  for communication to the other endpoints in the conference VTG, or IS  100  may otherwise facilitate communications among the endpoints. Since endpoint  80  is part of a conference of half-duplex endpoints, it must “control the floor” in order to have its communications transmitted to and received by the other, half-duplex endpoints of the conference. Otherwise, its outgoing communications may not reach a half duplex endpoint  90  that is currently sending a communication of its own and vice versa, since half duplex endpoints  90  communicate through a single channel. This floor control may be provided to endpoint  80  by IS  50  through a mute function. For example, when endpoint  80  is not muted, it controls the floor such that its communications are transmitted to PTT endpoints  90  of the VTG. IS  100  will prevent users of half duplex endpoints  90  from gaining control of the floor at this time. However, when endpoint  80  is muted, then one of PTT endpoints  90  may be able to control the floor to communicate to the rest of the VTG, including to endpoint  80 . The mute function may be activated and deactivated by the user of endpoint  80  through any suitable method, such as through a DTMF button of the endpoint which transmits a DTMF signal in the communication channel through which endpoint  80  communicates with IS  50 . In some embodiments, IS  50  may force full duplex endpoint  80  into mute whenever a half duplex endpoint gains floor control.  
      When endpoint  80  calls into a VTG comprising one or more half-duplex devices (e.g., endpoints  90 ), IS  100  may automatically mute the endpoint and may notify its user that the endpoint is on mute. When IS  100  mutes endpoint  80 , it may prevent its communications, such as its RTP packet stream in particular embodiments, from reaching the other endpoints of the VTG. IS  100  may provide the user of endpoint  80  with the instructions of how to un-mute (e.g., pressing DTMF button  1  on his endpoint) and how to mute (e.g., pressing DTMF button  0  on his endpoint). In some cases, the same DTMF button may be used to mute and un-mute the endpoint.  
      When the user of endpoint  80  desires to “control the floor” in order to communicate with the half-duplex endpoints  90  of the VTG, the user may un-mute the endpoint. Upon receiving the command to un-mute (e.g., through a DTMF signal), IS  100  transmits a typical floor control signal to the other, half-duplex endpoints  90  such that they are not allowed to communicate in the VTG. This is similar to the manner in which a typical PTT endpoint prevents other PTT endpoints communicating on a channel from communicating when the first PTT endpoint controls the floor. After making his desired communications, the user of endpoint  80  may subsequently mute the endpoint in order to allow another endpoint to control the floor and communicate on the VTG.  
      In particular embodiments, IS  100  may utilize the fact that endpoint  80  is connected via a full duplex connection (e.g., another communication channel will be available to communication with endpoint  80 ) and may provide an audible signal to the user of endpoint  80  in order to give him feedback that endpoint  80  is unmuted and thus has the floor. This may be similar to the typical PTT context whereby when a user of a PTT, half-duplex endpoint presses his “talk” button, he receives an audible signal when he has floor control allowing his communications to be received by the other PTT endpoints communicating on the same channel. The audio signal may comprise, for example, a “boink” sound signifying the granting of floor control by IS  100  to endpoint  80 .  
      In particular embodiments, IS  100  may utilize other methods to signal to a user of endpoint  80  that endpoint  80  has control of the floor. In some cases, IS  100  may transmit a visual indicator (e.g., LED, instant message, e-mail, flash display, etc.) to endpoint  80  to signify floor control. In some embodiments, IS  100  may provide floor control confirmation to endpoint  80  through vibrations. In other embodiments a user of endpoint  80  may have another, associated endpoint to which a floor control confirmation signal may be transmitted, whether audio, visual or otherwise. For example, endpoint  80  may comprise a full duplex telephone and the user of endpoint  80  may also have another endpoint, such as a PC, coupled to IS  100 . IS  100  may transmit a floor control confirmation signal to the PC endpoint. This confirmation signal could be in any suitable form, such as an instant message, e-mail or otherwise.  
      If a user of endpoint  80  attempts to gain floor control (e.g., through a DTMF signal) when another endpoint such as one of PTT endpoints  90  has the floor, IS  100  may transmit a floor control denial signal to endpoint  80  or another endpoint associated with the user of endpoint  80  to notify the user that he cannot gain control of the floor at that time. In particular embodiments, such floor control denial signal may comprise an audio “bonk” transmitted to endpoint  80 . In other embodiments, such floor control denial signal may comprise another audio signal or a visual or vibratory signal transmitted to endpoint  80  or another endpoint associated with the user of endpoint  80  and coupled to IS  100 , such as those described above with respect to the floor control confirmation signal.  
      In some embodiments, IS  100  may attempt to prevent a user of full-duplex endpoint  80  from controlling the floor for an extended amount of time (e.g., “locking the channel”) since, while the user controls the floor, he has the channel locked such that other PTT endpoints are prevented from communicating in the VTG. For example, if IS  100  determines that a user is talking longer than a particular amount of time (e.g., 2 minutes), the system may utilize the full duplex capability of the communication channel to endpoint  80  to signal the user that he is about to be muted. In some cases, the user may not be talking and may have forgotten that endpoint  80  was un-muted such that he had control of the floor preventing endpoints  90  from communicating. Such a signal may take the form of an audible tone or other signal, such as a whisper indication. In some cases, IS  100  may not signal the user of endpoint  80  that he is about to be muted and may automatically mute the endpoint when a maximum talk time is reached.  
      In some embodiments, IS  100  may have a policy that determines the maximum amount of time that a particular user may control the floor (e.g., a maximum talk time). This maximum talk time may vary by user. For example, higher priority users (e.g., higher ranked users or users in higher positions within an organization) may be allotted a longer maximum talk time. In some cases, a maximum talk time for a user communicating on a full duplex endpoint in a VTG with users of half-duplex devices may vary based on a type or priority of an event associated with the VTG. For example, higher priority events or events of a particular type (e.g., a terrorist event) may allow a shorter or longer maximum talk time while lower priority events or events of another type (e.g., a car accident) may allow a different maximum talk time.  
      As described above, IS  100  enables a user of full duplex endpoint  80  to participate in PTT communications with, for example, PTT endpoints even though full duplex endpoint  80  may not understand or otherwise be capable of such participation.  
       FIG. 4A  illustrates a system for providing a push-to-talk communication session using a control endpoint, in accordance with a particular embodiment. The illustrated embodiment includes a full duplex endpoint  120 , a control endpoint  122  and a plurality of half-duplex endpoints  130  coupled to an IS  140 . Similar to  FIG. 3 ,  FIG. 4A  is only a logical illustration, and endpoints  120 ,  122  and  130  may be coupled to IS  140  through any of a number of communication networks, such as an IP network. In some cases, communications between the illustrated endpoints may not travel through IS  140  but may travel through gateways and other network components controlled by an IS. While not specifically illustrated, endpoints  120 ,  122  and  130  may be coupled to IS  140  through one or more separate communication networks, such as land mobile radio networks of separate groups or supporting communication on separate frequencies, as discussed above with respect to endpoints  80  and  90  of  FIG. 3 . Communication paths from endpoints  120  and  122  may traverse different networks. For example, a communication path from endpoint  120  may traverse a PSTN network, and a communication path from endpoint  122  may traverse a WAN.  
      In particular embodiments, endpoints  120 ,  122  and  130  may comprise endpoints of different communication networks, such as endpoints of different police departments, fire departments or other security agencies or groups. Endpoints  120  and  130  (including endpoints  130   a - 130   c  individually) may typically communicate on their own communication networks on frequencies; but in this case their communications are bridged through IS  140  for interoperable communication with each other in a virtual talk group using Internet Protocol. IS  140  may be similar to, and may provide similar functionality as, IS  50  discussed above.  
      Full duplex endpoint  120  and control endpoint  122  may each comprise any suitable transmitter/receiver, user interface, processor and memory module. In some cases, full duplex endpoint  120  may comprise a rotary phone incapable of transmitting DTMF or other control signals to IS  140 .  
      In the illustrated embodiment, two different communication paths or channels are used to provide full duplex endpoint  120  with the ability to effectively communicate with half-duplex endpoints  130 . One communication path or channel may be used as a data channel to communicate the audio information, while another communication path or channel may be used as a control channel to communicate PTT controls. Particular embodiments may terminate the data and control paths at the same, full duplex endpoint such as endpoint  120 . However, as illustrated, in some embodiments the data path and the control path may terminate at different devices or endpoints. For example, a data communication path from endpoint  120  carries the audio that the user of endpoint  120  requests to communicate to the users of endpoints  130  in the VTG. A control communication path from endpoint  122  carries the PTT floor control signal used by the user of control endpoint  122  to speak on the VTG. This control signal may be transmitted by the user through control endpoint  122 , which is separate from endpoint  120  used by the user to talk on the VTG. In some cases, the user may authenticate himself at endpoint  122 . This authentication will associate his use of endpoint  122  with his audio transmissions from endpoint  120  to allow the user to communicate in a PTT manner on endpoint  120  using endpoint  122  as a floor control device.  
      The illustrated embodiment utilizes a signaling method for controlling the PTT and floor control on behalf of full duplex endpoint  120 . Control endpoint  122  may be used to implement a self-moderated PTT control and may include a separate PTT button  121  to control the floor through the control path. Control endpoint  122  may comprise any of a number of types of endpoints, such as a PC, a PDA or an IP phone and may interface with IS  140  to control the floor on PTT communications of full duplex  120  using any suitable interface, such as a web interface. For example, a separate button&#39;s floor control functionality may be implemented through HTTP or XML in some cases. In some cases, floor control may be provided through a PTT soft button on, for example, a PDA or through a hardware device such as a foot switch. In some cases, floor control may be provided via instant messaging between a user and an IS. A user of endpoint  120  may be in a PTT VTG (provided through or facilitated by IS  140 ) with half-duplex endpoints  130 . Endpoint  122  includes PTT button  121  used by the user when the user wishes to gain floor control in order to communicate to the group. When the user desires to talk, he may press and hold PTT button  121 . A floor control request signal is then sent to IS  140  which then sends a signal to half duplex endpoints  130  indicating that endpoint  120  has the floor to talk. IS  140  may also send a floor control confirmation signal (e.g., audio, video, vibratory or otherwise) to endpoint  120 , endpoint  122  or both to notify the user that he has control of the floor. The user may then talk through endpoint  120 , and the user&#39;s audio may be communicated from endpoint  120  (e.g., through IS  140  or otherwise) for transmittal to endpoints  130  of the VTG. Similarly, if another endpoint has control of the floor when the user sends the floor control signal via endpoint  122 , then IS  140  may transmit a floor control denial signal to endpoint  120 , endpoint  122  or both to notify the user that he cannot gain control of the floor at that time. A user may also control other PTT functionality through control endpoint  122 , such as activation, deactivation, configuration functions, mute and un-mute.  
      It should be understood that particular embodiments may vary in the manner in which a user controls the floor through control endpoint  122 . For example, in some cases the user may press button  121  to take control of the floor and then press it again to relinquish floor control. In some cases multiple buttons may be used. Some embodiments may not use a button but may instead use another type of interface, such as a touch screen display of control endpoint  122 . Particular embodiments contemplate great flexibility in the manner in which the PTT control signal is activated or used to control the floor to enable the user of endpoint  120  to communicate in the VTG in a PTT manner with endpoints  130 . Using a separate endpoint as the source for the PTT control signal provides particular advantages, including the ability to utilize a full duplex endpoint that does not have DTMF capability (e.g., an older rotary phone) in the PTT environment provided for full duplex endpoints through an IS.  
      In some embodiments that utilize separate channels for data and control, such separate channels may terminate at the same endpoint. For example, in some cases both the data path and control signal path may terminate at endpoint  120 , and endpoint  120  may include PTT button  121  or other suitable interface for floor control. This is similar to the embodiments discussed with respect to  FIG. 3  in which endpoint  80  was used both for the audio communications and to gain control of the floor to speak. However, as discussed above, in embodiments described with respect to  FIG. 4A  the control signal is communicated in a different path (i.e., a control path) than the main talk or audio stream; and in  FIG. 3  the control signal was communicated in the main talk or data stream (e.g., through DTMF signaling in that stream).  
       FIG. 4B  illustrates another example of the use of a separate path or channel for the control signaling used by a plurality of users of a full duplex endpoint to communicate in a PTT virtual talk group. In the illustrated embodiment, full duplex endpoint  120  may be a phone in a conference room or another endpoint usable by multiple users to participate in a PTT VTG with half duplex endpoints  130 . Control endpoints  126  are coupled to IS  140  and are used by each user individually to provide PTT floor control for the users. Control endpoints  126  may comprise any suitable device for communicating a PTT control signal to IS  140 , such as a cell phone (endpoint  126   a ), a PC (endpoint  126   b ) or a PDA (endpoint  126   c ). As described above with respect to endpoints of other embodiments, full duplex endpoint  120 , endpoints  126  and half duplex endpoints  130  may be coupled to IS  140  through one or more communication networks, such as one or more WANs, LANs, cellular networks, PSTNs, LMR networks, CDMA networks, GSM networks, TDMA networks or satellite networks.  
      As an example in operation, endpoint  120  may be a full duplex conference phone in a conference room and may be used to provide communications in a VTG through IS  140  with PTT endpoints  130 . Control endpoints  126   a - 126   c  may each comprise an endpoint of a respective person in the conference room. Each such person uses endpoint  120  to talk on the VTG conference. Conference communications may be transmitted from endpoint  120  for communication to endpoints  130 . However, each such person may use his respective endpoint  126  to control the floor of the conference when he desires to talk. Such PTT floor control signals are transmitted to IS  140  from the respective endpoint  126  along a control path (e.g., in a similar manner as discussed above with respect to  FIG. 4A ). For example, when a user of cell phone endpoint  126   a  desires to talk on the conference, he may press and hold a PTT button on his cell phone. This sends a floor control signal to IS  140  which is transmitted to endpoints  130  to indicate that a user of endpoint  120  has the floor. The cell phone user then speaks or otherwise communicates on the conference through endpoint  120 . The conference communications are communicated to IS  140  along a data path from endpoint  120 . Similarly, when a user of PDA  126   c  desires to communicate on the VTG conference, he may gain control of the floor by a control signal transmitted from endpoint  126   c  along a control between endpoint  126   c  and IS  140 . The user may then talk on the conference through endpoint  120 . As is the case with other embodiments, any number of interfaces or floor control activation methods may be used, including web interfaces through endpoints  126 . In some embodiments, the control signals may be transmitted from endpoints  126  to endpoint  120  for communication to IS  140 . In this way, they may be transmitted from endpoint  120  to IS  140  along a control path separate from the data path from endpoint  120 .  
      In some cases, IS  140  may determine and identify a particular speaker based on the endpoint from which the PTT control signal is transmitted. For example, when communication is made from endpoint  120  after a user gains floor control using his cell phone endpoint  126   a , IS  140  may determine that the person speaking is the user associated with endpoint  126   a . This may be useful to other users of IS  140  in determining the identity of a particular speaker out of a plurality of people in a conference room all using a full duplex conference room phone such as endpoint  120  for their VTG communications.  
       FIG. 5  illustrates a system  200  for providing a proxy media service, in accordance with a particular embodiment. System  200  includes users  202  and  204  who monitor push-to-talk communications of VTGs provided by IS  210 . IS  210  may be similar to IS  50  described above and may enable interoperable VTG communications among endpoints of different communication networks. In particular cases, users  202  and  204  may desire to monitor at one time, through IS  210 , communications from a plurality of different VTGs supported by the IS, each VTG comprising a conference media stream of PTT communications of respective endpoints of the VTG. In some cases, such users may monitor communications from eight separate PTT VTG groups and may therefore receive eight separate media streams.  
      User  204  may access IS  210  through endpoint  205 , which may comprise any suitable endpoint for receiving multiple streams of PTT communications for monitoring, such as a PC endpoint accessing the OMA of IS  210  and running a PC media client of the IS. Endpoint  205  is coupled to IS  210  through a high bandwidth network  206 , in this case a LAN. IS  210  may transmit a communication stream for each of the plurality of monitored VTGs, collectively communication streams  215 , to endpoint  205  via high bandwidth network  206 . As indicated above, in some cases communication streams  215  may comprise up to eight different media streams each from a monitored channel of PTT VTG communications. Endpoint  205  may then mix each of the communications streams  215  for communication to user  204  through a speaker or otherwise. In some cases, user  204  may use endpoint  205  for changing the volume of one or more of the streams  215  with respect to another of the streams or for providing other control functionality.  
      In some situations, a user&#39;s access to IS  210  may be provided through a low bandwidth network that is only able to effectively communicate audio from one PTT VTG channel at one time. Thus, the low bandwidth network is not able to effectively communicate the plurality of monitored PTT VTG communications in a separate stream for each VTG (e.g., in some cases this may include eight streams) as can be done for endpoint  205  accessing the IS through a LAN&#39;s high bandwidth connection. For example, a user may be accessing IS  210  via a low bandwidth WAN, such as through a DSL connection from home or away from a LAN at an office to which the IS is coupled. In particular embodiments a proxy media service may be used to mix the monitored streams into one stream for effective communication to the user through the WAN. Likewise, the proxy media service may also receive communications from the user over the WAN for communication over one or more of the monitored streams (or VTGs). The proxy media service may also utilize a control path over the WAN to provide control functionality to the user as desired. Examples of this control functionality are further discussed below. Therefore, particular embodiments provide a user connected over a low bandwidth WAN similar functionality and services for monitoring, communicating and with controlling a plurality of PTT VTGs as that provided to a user connected through a high bandwidth LAN.  
      As an example in operation, user  202 , utilizing endpoint  203 , accesses IS  210  through low-bandwidth WAN  208 . Endpoint  203  may comprise any suitable endpoint accessing the OMA of IS  210  and running a PC media client of the IS. In this example, since endpoint  203  is coupled to IS  210  through a low bandwidth network, the individual communication streams from the monitored PTT VTGs are communicated to a proxy media service (PMS)  220 . IS  210  may transmit, direct and/or facilitate such communication. For example, IS  210  may instruct PMS  220  to listen to a particular multicast stream to enable PMS  220  to receive the communications on the stream. In some cases the communication streams may be sent from IS  210  to PMS  220 . The media streams are collectively illustrated as communication streams  224  and may comprise a plurality of streams, each for a separate monitored PTT VTG channel. In some cases communication streams  224  may include eight streams.  
      In the illustrated embodiment, PMS  220  includes a processor  221 , a database  222  and a mixer  223 . Processor  221  may be a microprocessor, controller, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other PMS  220  components such as mixer  223 , PMS  220  functionality. Memory module  222  may be any form of volatile or non-volatile memory including, without limitation, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. Memory module  222  may store any suitable data or information, including software and encoded logic, utilized by PMS  220 .  
      Mixer  223 , in conjunction with processor  221 , mixes the individual communication streams  224  received at PMS  220  into one stream so that the media may be effectively communicated to endpoint  203  via low bandwidth network  208 . Mixer  223  may comprise any hardware, software or encoded logic to provide its functionality.  
      Continuing the example described above, PMS  220  receives communication streams  224  and mixes them into one stream for communication to endpoint  203  of user  202 . The mixed stream of the plurality of communication streams  224  is represented as communication stream  225 . Communication stream  225  travels to endpoint  203  through low bandwidth network  208  and, as discussed above, includes in one stream communications from each of a plurality of PTT VTGs enabled by IS  210  that user  202  desires to monitor. In some cases, this may include up to 8 separate PTT streams mixed into communication stream  225 . In some embodiments, endpoint  203  may be connected to PMS  220  through a nailed connection.  
      In some embodiments, PMS  220  may also transmit to endpoint  203  an identification of a VTG channel from which a particular communication comes. This may be displayed to user  202  by endpoint  203 . This is particular helpful to user  202  since endpoint  203  is receiving a single stream  225  that comprises communications originating from a plurality streams. For example, user  202  may monitor VTGs  1 - 8  that are enabled by IS  210 . A particular communication from, for example, VTG  5  may be mixed into stream  225  and transmitted to endpoint  203 . Since user  202  is monitoring 8 different VTGs, he would not otherwise know that the particular communication came from VTG  5  if not notified of this by PMS  220 . Thus, PMS  220  may transmit information signifying the channel of VTG  5  as the source of a particular communication sent in communication stream  225 .  
      In addition, endpoint  203  may be able to receive communications on a plurality of channels. User  202  may, through a button of endpoint  203  or otherwise, notify PMS  220  of a particular channel in which to transmit mixed communication stream  225 . For example, if the user selects channel B, then PMS  220  may receive communication streams  224  each communicated on a different channel, mix them into one stream  225  and transmit this stream to endpoint  203  on selected channel B.  
      In particular embodiments, user  202  may utilize a signaling or control channel between the endpoint and PMS  220  for controlling various features of PMS  220 . For example, if the user wanted to change the volume of a particular channel in the mixed stream  225 , the user may transmit such a request along the control path. In response, mixer  223  and processor  221  may change the volume of the particular VTGs communications relative to the other VTGs when mixing the communications from the various VTGs. The volume change will then be represented in mixed stream  225  communicated to endpoint  203 .  
      A separate control or signaling path may also carry other user selections, such as a selection of a particular VTG channel to mix into stream  225 . For example, IS  210  may be providing other VTGs that are not currently mixed into stream  225 . User  202  may select one or more other such channels through the control or signaling path and PMS  220 , in response, may receive communications from the selected VTG(s) and mix them into stream  225  for communication to endpoint  203 . Other control functionality that may be provided through the control path may include activation and deactivation of particular VTG streams (for transmission by PMS  220  and receipt at endpoint  203 ) and mute and un-mute of particular streams.  
      In addition, in particular embodiments user  202  may transmit communications to one or more of the VTG streams over the WAN. For example, the user may use endpoint  203  to speak, and such spoken communication may be transmitted to PMS  220  for communication in one or more of the PTT VTGs, through multicast, SIP nailed dialed connection, bridged communication or otherwise facilitated by IS  210 . Thus, PMS  220  enables the user to communicate a single stream over the WAN for communication to a plurality of VTG streams instead of the user having to communicate (over the WAN) separate streams for each of the VTGs the user desires to receive the communication.  
      The user may use the control path to identify a subset of the streams monitored by the PMS  220  to which the user&#39;s communications will be transmitted. For example, PMS  220  may be monitoring and mixing 8 VTG streams for transmission to endpoint  203 . However, the user at a particular time may only desire to speak on 3 of such streams. Thus, the user may use a PC softkey or other mechanism to identify the three streams to which a particular communication from the user should be transmitted. This identification of the streams to which a particular communication from the user should be transmitted may be undertaken by a selection or other activation of the stream at the user endpoint. Then, when the user speaks, his communication is transmitted in a single stream to PMS  220  which then forks the communication to the identified streams. PMS  220  may transmit to the endpoint through an LED or other notification an identification of the selected streams to which the user&#39;s communication is transmitted. Thus, particular embodiments enable the user to provide latch and unlatch speaking functionality over a control path to one or more of the streams monitored at PMS  220 . This is advantageous since many services providing internet connections over a WAN, such as many DSL services, provide a lower bandwidth for upstream communications than that provided for downstream communications.  
      In particular embodiments, a system may, for example through PMS  220 , have the ability to continuously analyze the available bandwidth over WAN  208  and the number of communication streams that the user wishes to monitor and/or participate in. Based on this analysis, the system may determine whether to use the mixing capabilities of PMS  220  to mix such streams at the PMS or whether to send or receive the separate streams from endpoint  203 . For example, if user  202  desires to receive and/or communicate in 6 separate communication streams facilitated by IS  210  and enough bandwidth exists over WAN  208  to convey each separate stream at an appropriate quality level, then the streams may be individually transmitted to endpoint  203  without mixing at PMS  220  and the user may communicate on the streams by endpoint  203  transmitting separate communications for each stream over WAN  208 . If, however, enough bandwidth does not exist over WAN  208  to convey each separate stream at a specified or appropriate quality level, then the streams may be mixed at PMS  220  for transmission as a mixed stream over WAN  208  to endpoint  203  as discussed above. Moreover, as discussed above a single communication stream from the user may be transmitted over WAN  208  (e.g., “upstream”) and may be forked at PMS  220  for transmission on the user&#39;s specified talk groups or channels. In this case, endpoint  203  may include a processor (e.g., similar to the processor of PMS  220 ) or other hardware, software or logic component for monitoring the bandwidth over WAN  208  and determining whether to send a user communication in a single stream upstream to PMS  220  for forking at PMS  220  to each of a user-selected number of VTG streams or whether to send separate streams over WAN  208  from the user endpoint for transmission to each of the user-selected number of VTG streams. As indicated above, the determination may be based on whether the transmission of the separate individual streams over WAN  208  can be accomplished at a specified or appropriate quality level. The acceptable service level needed to make the determination over whether to use PMS  220  for mixing/forking may be determined, for example, by a system operator or administrator or otherwise. Call admission control functionality may be used in this process for making such determination.  
      In some embodiments, user  202  may communicate on the monitored VTGs mixed into stream  225  in a similar manner as discussed above with respect to embodiments providing PTT communication ability to full duplex endpoints. In this case, PMS  220  may analyze and embed specific PTT tones to provide the user appropriate boinks and bonks such that the user experience looks and feels like a native PTT user even though the full duplex device has no knowledge of floor control.  
      As indicated above, particular embodiments provide a user connected over a low bandwidth WAN similar functionality and services for monitoring, communicating and with controlling a plurality of PTT VTGs as that provided to a user connected through a high bandwidth LAN. Thus, the appearance to the end user of LED and other indicators related to the PTT monitoring system&#39;s functionality will be the same regardless of whether mixing occurs using a proxy media service or whether the user&#39;s endpoint actually can receive/transmit and mix for presentation to the user separate streams for each monitored stream. As discussed above, these indicators may be used to indicate, for example, which stream(s) are currently being monitored, on which stream(s) a particular user communication is currently being transmitted (e.g., latch/unlatch notification), floor control, mute/unmute and other functionality. In addition, the PTT functionality for the end user may be the same regardless of whether the user is accessing the system over a WAN or a LAN. Thus, the PTT functionality provided to the end user may be independent of the user&#39;s location.  
       FIG. 6  is a flowchart illustrating a method for providing a push-to-talk communication session, in accordance with a particular embodiment. The method begins at step  300  where a push-to-talk communication session among a full duplex endpoint and a plurality of half duplex endpoints is facilitated. The full duplex endpoint may support simultaneous two-way communication to and from the endpoint. The half duplex endpoints may only be able to either transmit or receive communications at one time. Communications are received from and transmitted to the full duplex endpoint along a two-way communications path. The half duplex endpoints may include endpoints of different communication networks, such as endpoints that typically communicate on different frequencies. The communication session may be facilitated using IP by an interoperability system bridging communications or controlling gateways or other network components.  
      At step  302 , communications received from the full duplex endpoint are blocked while one of the plurality of half duplex endpoints has floor control in the communication session. At step  304 , a floor control signal is received from the full duplex endpoint in the two-way communications path. The floor control signal comprises a request to transmit communications in the communication session and may comprise a DTMF signal.  
      At step  306 , in response to receiving the floor control signal, floor control is provided to the full duplex endpoint to allow a user of the full duplex endpoint to communicate in the communication session. In some cases, a confirmation signal such as a bonk may be transmitted to the full duplex endpoint to signify that the full duplex endpoint has control of the floor. The floor control confirmation signal may include any suitable audio, visual or vibratory signal. In some embodiments, the floor control confirmation signal may be transmitted to another endpoint associated with the user of the full duplex endpoint, such as through an instant message, an e-mail, or another visual signal to a PC of the user. At step  308 , communications received from the full duplex endpoint are transmitted to the plurality of half duplex endpoints.  
      In some cases, the full duplex endpoint is only allowed to maintain control of the floor for a certain amount of time. At step  310 , floor control of the full duplex endpoint is terminated after a maximum floor control amount of time to allow the half duplex endpoints to communicate in the communication session. The maximum floor control amount of time may be determined based on a particular user of the full duplex endpoint, an event associated with the communication session or other factors.  
       FIG. 7  illustrates a method for providing a push-to-talk communication session using a control endpoint, in accordance with a particular embodiment. The method begins at step  400  where a push-to-talk communication session among a full duplex endpoint and a plurality of half duplex endpoints is facilitated. The full duplex endpoint may support simultaneous two-way communication to and from the endpoint. The half duplex endpoints may only be able to either transmit or receive communications at one time. Communications are received from and transmitted to the full duplex endpoint along a two-way communications path. The half duplex endpoints may include endpoints of different communication networks, such as endpoints that typically communicate on different frequencies. The communication session may be facilitated using IP by an interoperability system bridging communications or controlling gateways or other network components.  
      At step  402 , communications received from the full duplex endpoint are blocked while one of the plurality of half duplex endpoints has floor control in the communication session. At step  404 , a floor control signal is received from a control endpoint separate from the full duplex endpoint. The floor control signal comprises a request to transmit communications in the communication session. In some cases the control endpoint may be a user&#39;s cell phone, PC, IP phone or PDA. In some cases the control signal may be received via a web, instant messaging, HTTP or XML interface.  
      At step  406 , in response to receiving the floor control signal, floor control is provided to the full duplex endpoint to allow a user of the full duplex endpoint to communicate in the communication session. In some cases, a confirmation signal such as a bonk or boink may be transmitted to the user of the full duplex endpoint, for example through the full duplex endpoint, the control endpoint or otherwise, to signify that the full duplex endpoint has control of the floor. At step  408 , communications received from the full duplex endpoint are transmitted to the plurality of half duplex endpoints. It should be understood that although “bonk” and “boink” are used to describe audio sounds herein, it should be understood that any suitable audio sound may be used to convey the applicable messages or indications as those conveyed by the described bonks and boinks.  
      In some embodiments the full duplex endpoint may be used by a plurality of users to communicate in the communication session, and each of the plurality of users may transmit a control signal to gain floor control in the session using their own respective devices, such as cell phones, PDAs, PCs and IP phones. As an example, the plurality of users may be sitting in a conference room in which the full duplex endpoint sits. When a particular user in the room desires to speak in the session, the user may transmit a floor control request signal from that user&#39;s personal endpoint. The floor signal may be received at an interoperability system facilitating the communication session which then provides the user with floor control to speak in the session. In some cases in which multiple endpoints are used to gain control of the floor to speak through a full duplex endpoint, the system may identify a particular speaker based on the endpoint used to transmit the push-to-talk floor control signal.  
       FIG. 8  illustrates a method for providing a push-to-talk proxy media service, in accordance with a particular embodiment. The method begins at step  500  where a plurality of monitored communication streams, such as push-to-talk communication streams, are received over a high bandwidth connection. The communication streams may be monitored at an interoperability system that facilitates interoperable communications in virtual talk groups among endpoints of various communication networks. The monitored streams may be received at a proxy media system coupled to a high bandwidth network to which the interoperability system is coupled.  
      At step  502 , the plurality of monitored push-to-talk communication streams are mixed into a mixed communication stream. Such mixing may take place at the proxy media system. At step  504 , the mixed communication stream is transmitted over a low bandwidth connection to a user endpoint. For example, a user may be using a low bandwidth network such as a WAN to access a high bandwidth network, such as a LAN, from a home computer or other endpoint away from the LAN. The proxy media system may be coupled to the LAN and may transmit the mixed communication stream to the user over the low bandwidth WAN.  
      As indicated above, in some cases the monitored communication streams may each comprise a stream of a virtual talk group configured by an interoperability system. In some cases, at step  506 , an identification of a particular speaker&#39;s or communication&#39;s virtual talk group may be transmitted to the user (e.g., in the mixed stream). For example, if the mixed stream at one point includes communications from VTG  4 , then an identification of VTG  4  may be transmitted when such communication from VTG  4  is transmitted to the user.  
      In some embodiments, the user endpoint may use a separate control path to transmit instructions to the proxy media system, such as instructions to adjust the volume of a particular VTG&#39;s stream relative to other VTGs&#39; streams when mixing the monitored communication streams. In some cases the user endpoint may be operable to receive the mixed stream on any of a number of channels, and the user endpoint may use the separate control path to transmit a channel selection for receipt of the mixed stream. In addition, in some embodiments the user endpoint may, through the control path, instruct the proxy media system to mix certain streams (e.g., streams from certain, selected VTGs) out of all the monitored communication streams received from the interoperability system.  
      Some of the steps illustrated in  FIGS. 6-8  may be combined, modified or deleted where appropriate, and additional steps may also be added to the flowcharts. Additionally, steps may be performed in any suitable order without departing from the scope of the invention.  
      While various implementations and features are discussed with respect to multiple embodiments, it should be understood that such implementations and features may be combined in various embodiments. For example, features and functionality discussed with respect to a particular figure may be used in connection with features and functionality discussed with respect to another such figure according to operational needs or desires.  
      Although the present invention has been described in detail with reference to particular embodiments, it should be understood that various other changes, substitutions, and alterations may be made hereto without departing from the spirit and scope of the present invention. For example, although the present invention has been described with reference to a number of elements included within communication system  10  and illustrated endpoints and interoperability systems, these elements may be combined, rearranged or positioned in order to accommodate particular routing architectures or needs. In addition, any of these elements may be provided as separate external components to communication system  10  and illustrated endpoints and interoperability systems, or each other where appropriate. The present invention contemplates great flexibility in the arrangement of these elements as well as their internal components.  
      Numerous other changes, substitutions, variations, alterations and modifications may be ascertained by those skilled in the art and it is intended that the present invention encompass all such changes, substitutions, variations, alterations and modifications as falling within the spirit and scope of the appended claims.