Patent Publication Number: US-9838441-B2

Title: Hybrid communications system using peer-to-peer and centralized architecture

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/681,309, filed Apr. 8, 2015, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     This disclosure generally relates to electronic audio and/or video communications between multiple parties in enterprise networks and, more particularly, to a hybrid communication system that uses a peer-to-peer and centralized architecture for such communications. 
     The types of devices and services that users employ to effect electronic communications with one another have expanded significantly in recent years. For example, whereas users once used phones solely to engage in audio communications with one another, devices (e.g., smart phones) now enable people to engage in a wide variety of different types of electronic communications with one another, including video conferencing, text messaging, email, instant messaging, and location sharing. 
     Typically a centralized server mediates communications between two devices on an enterprise network in a media session, and users do not have an option of switching an established media session to some peer-to-peer connection of potentially higher bandwidth. Similarly, two electronic devices conducting a media session over a peer-to-peer connection do not have an option of switching the established media session over to some other peer-to-peer connection and/or centralized server connection that has better bandwidth. Aspects of the disclosed embodiments address these and other concerns regarding communications between electronic devices in enterprise systems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a hybrid communication environment, according to an example embodiment of the present disclosure. 
         FIG. 2  is a high-level block diagram illustrating a detailed view of modules within the communications system according to an example embodiment 
         FIG. 3  is an interaction diagram of a process for establishing a hybrid media session using a hybrid communications system. 
         FIG. 4  is a wire diagram of a process for establishing a hybrid media session using a hybrid communications system, according to an example embodiment. 
         FIG. 5  is a wire diagram of a process for establishing a peer-to-peer session in the hybrid communications system of  FIG. 4 , according to an example embodiment. 
         FIG. 6  is a wire diagram of a process for establishing a peer-to-peer session channel between endpoints A and B via a peer-to-peer media relay node in the hybrid communications system of  FIG. 4 , according to an example embodiment. 
         FIG. 7  is a high-level block diagram illustrating an example computer for implementing the entities shown in  FIG. 1 . 
     
    
    
     The figures depict various example embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that other example embodiments based on alternative structures and methods may be implemented without departing from the principles of the disclosure. 
     DETAILED DESCRIPTION 
     The Figures and the following description describe certain embodiments by way of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein. Reference will now be made in detail to several embodiments, examples of which are illustrated in the accompanying figures. It is noted that wherever practicable similar or like reference numbers may be used in the figures and may indicate similar or like functionality. 
     The above and other needs are met by the disclosed methods, a non-transitory computer-readable storage mediums storing executable code, and systems for conducting a hybrid media session. 
     In one embodiment, a hybrid communications system performs a method for conducting a hybrid media session. The method comprises estimating a quality of service for each of a plurality of session channels available to couple a first electronic device on a first network with a second electronic device on a second network, the plurality of session channels including a peer-to-peer session channel and a server-controlled session channel. The hybrid communications system selects a first session channel, from the plurality of session channels, where the selected first session channel has a highest estimated quality of service of all the plurality of session channels over a first time interval. The hybrid communications system instructs the first electronic device via a first signaling channel and a second electronic device via a second signaling channel to establish a hybrid media session using the first session channel such that media data is communicated on the first session channel. The hybrid communications system monitors during the hybrid media session the estimated quality of service for the plurality of session channels, and responsive to the monitoring, selects a second session channel, from the plurality of session channels, where the selected second session channel has a highest estimated quality of service of all the plurality of session channels over a second time interval that occurs subsequent to the first time interval. Responsive to the selecting, the hybrid communications system instructs the first electronic device via the first signaling channel and the second electronic device via the second signaling channel to establish the hybrid media session using the second session channel such that media data is communicated on the second session channel and not the first session channel. 
     In another embodiment, a hybrid communications system for conducting a hybrid media session comprises a processor configured to execute modules and a memory storing the modules. The modules include a quality of service module configured to estimate a quality of service for each of a plurality of session channels available to couple a first electronic device on a first network with a second electronic device on a second network, the plurality of session channels including a peer-to-peer session channel and a server-controlled session channel. The quality of service module is also configured to select a first session channel, from the plurality of session channels, where the selected first session channel has a highest estimated quality of service of all the plurality of session channels over a first time interval. The modules also include a control server configured to instruct the first electronic device via a first signaling channel and a second electronic device via a second signaling channel to establish a hybrid media session using the first session channel such that media data is communicated on the first session channel. The quality of service module is also configured to monitor during the hybrid media session the estimated quality of service for the plurality of session channels, and responsive to the monitoring, select a second session channel, from the plurality of session channels, where the selected second session channel has a highest estimated quality of service of all the plurality of session channels over a second time interval that occurs subsequent to the first time interval. The control server is also configured to responsive to the selecting, instruct the first electronic device via the first signaling channel and the second electronic device via the second signaling channel to establish the hybrid media session using the second session channel such that media data is communicated on the second session channel and not the first session channel. 
     In another embodiment, hybrid communications system for conducting a hybrid media session comprises a processor configured to execute modules and a memory storing the modules. The modules include a quality of service module configured to estimate a quality of service for each of a plurality of session channels available to couple a first electronic device on a first network with a second electronic device on a second network, the plurality of session channels including a peer-to-peer session channel and a server-controlled session channel. The quality of service module is also configured to determine that a peer-to peer media session was established previously between the first electronic device and the second electronic device on the peer-to-peer session channel, and responsive to the determination, positively weight the quality of service for the peer-to-peer session channel relative to the server-controlled session channel. The quality of service module is also configured to select a first session channel, from the plurality of session channels, where the selected first session channel has a highest estimated quality of service of all the plurality of session channels over a first time interval. The modules also include a control server configured to instruct the first electronic device via a first signaling channel and a second electronic device via a second signaling channel to establish a hybrid media session using the first session channel such that media data is communicated on the first session channel. The quality of service module is also configured to monitor during the hybrid media session the estimated quality of service for the plurality of session channels, and responsive to the monitoring, select a second session channel, from the plurality of session channels, where the selected second session channel has a highest estimated quality of service of all the plurality of session channels over a second time interval that occurs subsequent to the first time interval. The control server is also configured to, responsive to the selecting, instruct the first electronic device via the first signaling channel and the second electronic device via the second signaling channel to establish the hybrid media session using the second session channel such that media data is communicated on the second session channel and not the first session channel. 
     A hybrid communications system has a number of advantages over conventional communication systems. The quality of session channels has a tendency to vary with time, such that for different time periods different session channels would provide the highest session quality. Conventional systems may conduct a media session from start to finish on a single session channel. In contrast, the hybrid communications system actively selects, monitors, and possibly changes which session channel a hybrid media session is occurring over as a function of the session channels quality of service. Accordingly, the hybrid communications system may provide users with a hybrid media session having an average quality of service that is higher than other conventional systems. 
     Additionally, in some embodiments, the hybrid communications system keeps open previously active session channels during a given hybrid media session. This provides the hybrid communications system a way to make one the previously active session channels again active, without having to spend time re-establishing that channel. 
     Another advantage is that as a plurality of session channels are available to conduct a hybrid media session, in the communication system is more robust. For example, if an active peer-to-peer session channel fails, the hybrid communications system can continue the hybrid media session using some other session channel (e.g., internet fails, and the hybrid communications system recovers the session via a cellular network or a public switched telephone network). 
       FIG. 1  is a block diagram of a hybrid communication environment  100 , according to an example embodiment of the present disclosure. The hybrid communication environment  100  includes devices  110   a  and  110   b , and  110   c  that are part of enterprise networks  120  and  125 , respectively, and each coupled by a network  130  to a hybrid communications system  150 . The devices  110   a ,  110   b , and  110   c  can also connect to one another via one or more types of peer-to-peer connections. Here, only three electronic devices and one hybrid communications system  150  are illustrated, but there can be multiple instances of each of these entities. For example, there can be hundreds of devices  110  in communication with one or more hybrid communications system  150 . 
     The network  130  provides a communication infrastructure between the devices  110  and the hybrid communications system  150 . The network  130  is typically the Internet, but can be any network, including but not limited to a Metropolitan Area Network (MAN), a Wide Area Network (WAN), a public land mobile network (PLMN) which is also referred to as a wireless wide area network (WWAN) or a cellular network, a public switched telephone network (PTSN), or some combination thereof. 
     The enterprise networks  120 ,  125  allow the electronic devices  110   a - c  to interact with the hybrid communications system  150 . In some embodiments, enterprise networks  120 ,  125  can be an enterprise or business system. In some embodiments, the enterprise networks  120 ,  125  includes more than one network and is located in multiple geographic areas. The enterprise networks  120 ,  125  each include one or more local area networks. In some embodiments, the local area networks use standard communications technologies and/or protocols. Thus, local networks, and in effect, the enterprise networks  120 ,  125  can include links using technologies such as Ethernet, 802.11 standards, worldwide interoperability for microwave access (WiMAX), WiFi, 3G, digital subscriber line (DSL), etc. Enterprise networks  120  and  125  are connected to the network  130  through firewall  140  and firewall  145 , respectively. 
     Each of the devices  110   a - c  can participate in media sessions with each other and/or other devices, and the devices  110   a - c  and/or other devices can be referred to as a device  110 . A device  110  is an electronic device, such as cell phone, smart phone, desktop phone with a display, audio and/or video conferencing device, tablet, computer, gaming console, or some other device. A media session refers to passing media data on one or more session channels for audio and/or video communications negotiated (or in the process of being negotiated) by two communications systems where media data is passed on the one or more session channels. A media session can have a “lifetime” from when it is initiated to when it is terminated. During the lifetime of a media session, data channels can be added and removed. 
     A session channel refers to the combination of a) a format for the media data of the session channel; and b) a transport method for transporting the media data between the two communications systems of the media session to which the session channel belongs. In general, the media data format of a session channel can be audio and/or video. More specifically, the media data format can be a standardized packet format such as, for example, the Real-time Transport Protocol (RTP) for streaming the audio and/or video media data in data packets over one or more packet-switched data networks between the two communications systems. The transport method can be any suitable method for establishing media data streams between the two communications systems. Some possible transport methods include, but are not limited to, the User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP). 
     A session channel can be centralized session channel  155 A,  155 B,  155 C or a peer-to-peer (P2P) session channel  160 A,  160 B,  160 C. A centralized session is one in which media data is received by the hybrid communications system  150  which then relays the media data to other devices  110  participating in the centralized session via centralized session channels that couple the participating devices  110  to the hybrid communications system  150 . For example, if a user of a participating device  110   a  speaks into a microphone associated with the device  110   a  during a centralized media session, the audio signal is encoded as media data by device  110   a , and then sent to the hybrid communications system  150  through a centralized session channel. The hybrid communications system  150  then relays the media data to other participating devices (e.g.,  110   b  and/or  110   c ) through their respective centralized session channels (e.g.,  155 B,  155 C), to be output by speakers at those devices so users of those devices can hear what the user of device  110   a  said. 
     A peer-to-peer (P2P) media session refers to a media session in which the media data of the P2P media session is not relayed between the two communications systems of the media session by the hybrid communications system  150  or some other central server that performs media data mixing and/or transcoding functions. Instead a P2P media session occurs over one or more P2P session channels. The transport methods of a P2P session channel can leverage Network Address Translation (NAT) traversal protocols for establishing media streams between the peer communications systems. Some possible NAT traversal protocols include the Session Traversal Utilities for NAT (STUN) protocol and the Interactive Connectivity Establishment (ICE) protocol.  FIG. 1  illustrates an example P2P session channel  160 A between devices  110   a  and  110   b , an example P2P session channel  160 B between devices  110   a  and  110   c , and an example P2P session channel  160 C between devices  110   b  and  110   c . While  FIG. 1  illustrates a single P2P channel between each of the devices  110   a ,  110   b , and  110   c , in some embodiments, one or more of the P2P session channels  160 A,  160 B,  160 C can be represent multiple P2P session channels. 
     A hybrid media session refers to a media session that passes media data on different session channels at different times during the hybrid media session based on which of the session channels has a highest quality of service (QoS). For example, in a hybrid media session media data can be passed on different session channels at different time intervals during the hybrid media session. In each of these time intervals, the session channel passing media data has the highest QoS. A given hybrid media session is associated with a plurality of session channels. The plurality of session channels includes one or more P2P session channels and one centralized session channel. An active channel is the session channel being used to pass media data for a particular time interval. 
       FIG. 1  illustrates a signaling channel  165 A,  165 B, and  165 C, between the hybrid communications system  150  and devices  110   a ,  110   b , and  110   c , respectively. The signaling channels are used to pass signaling data between the devices  110  and the hybrid communications system  150 . Signaling data is information used to control a hybrid media session, a media session, or both. Signaling data can include, for example, data for initiating, accepting, managing, changing session channel, and terminating an associated media session. Signaling data sent over signaling channels can conform to a signaling network protocol such as, for example, the Session Initiation Protocol (SIP) and the H.323 protocol. While  FIG. 1  illustrates a single signaling channel  165  between each of the devices  110   a ,  110   b , and  110   c  and the hybrid communications system  150 , in some embodiments, one or more of the signaling channels  165 A,  165 B,  165 C can be represent multiple signaling channels. 
     The hybrid communications system  150  establishes a hybrid media session via requests received on the signaling channels  165 A-C. As discussed below in detail with regard to  FIGS. 2 and 3 , the hybrid communications system  150  receives request to initiate hybrid media sessions via the signaling channels  165 A-C from one or more devices  110 . In some embodiments, the requests can include invitations to other devices  110  to participate in a hybrid media session with the requesting device  110 . The hybrid communications system  150  communicates with the other devices  110  to provide them an option of participating in the hybrid media session with the requesting device  110 . 
     The hybrid communications system  150  controls which session channels are used for hybrid media sessions between devices  110 . As discussed in detail below with regard to  FIGS. 2  and  3 , for a group of devices  110  requesting to participate in a hybrid media session, the hybrid communications system  150  determines a quality of service (QoS) for each of the plurality of session channels associated with the requested hybrid media session. The determined QoS is based on, for example, bandwidth, jitter, connection history information, voice quality, etc. The hybrid communications system  150  selects a session channel, of the plurality of session channels, that has a highest QoS. The hybrid communications system  150  then notifies the participating devices  110  of the selected session channel and instructs them to establish a hybrid media session via the selected channel. The selected session channel can be, e.g., one or more P2P connections or a centralized session channel. Additionally, as discussed in detail below with regard to  FIGS. 2 and 3 , in some embodiments where a P2P connection is selected the communications system can verify and/or update connection parameters (e.g., firewall access information, codecs, etc.) to facilitate establishment of the hybrid media session over the P2P connection. Moreover, the communications server  150  can configure the firewalls  140  and/or  145  that would not normally allow a P2P session to allow a P2P session for at least the duration of the P2P media session. 
     The hybrid communications system  150  monitors the QoS for each of the plurality of session channels associated with the hybrid media session. If the hybrid communications system  150  identifies a session channel, other than the active session channel, as having a highest QoS, the hybrid communications system  150  instructs the participating devices  110  to establish the hybrid media session on the identified session channel. In some embodiments, the hybrid communications system  150  also instructs the participating devices  110  to keep the previously active session channel open (i.e., do not terminate the connection), in effect “pausing” use of the previously active session channel. Additionally, if at some later time a third session channel has the highest QoS, the hybrid communications system  150  instructs the participating devices  110  to establish the hybrid media session on the identified third session channel and keep the other two session channels open. As the hybrid media session continues, the hybrid communications system  150  instructs the participating devices  110  to provide media data on whichever session channel has the highest QoS. This allows a hybrid media session established in the hybrid communication environment  100  to change established session channels without having to spend time terminating and re-establishing session channels. 
     In other embodiments, if the hybrid communications system  150  identifies a session channel, other than the active session channel, as having a highest QoS, the hybrid communications system  150  instructs the participating devices  110  to establish the hybrid media session on the identified session channel, and terminate the previously active session channel. In this manner, the hybrid communications system  150  and/or the participating devices  110  are not expending system resources keeping a session channel open that is not being used. 
     The QoS of a particular session channel has a tendency to vary with time. For example, sudden network loads my negatively affect bandwidth of an associated session channel. Conventional systems can conduct a media session from start to finish on a single session channel, and thus QoS can vary significantly for a given media session. In contrast, the hybrid communications system  150  actively selects, monitors, and possibly changes which session channel a hybrid media session is occurring over as a function of the session channels QoS. Accordingly, the hybrid communications system  150  can provide users with a hybrid media session having an average QoS that is higher than other conventional systems. 
     In some embodiments, the hybrid communications system  150  operates in a client-server architecture, where hybrid communications system  150  serves client devices such as devices  110   a - c  based on any requests received from the client devices. Some of the functions that hybrid communications system  150  can perform include receiving, hosting, storing, and providing data associated with location of the client devices as well as contextual information items associated with the device location. For example, the hybrid communications system  150  includes some or all of: an email server, fax server, application server, communications server, database server, and a group of remote servers. In some example embodiments, hybrid communications system  150  can provide virtual private branch exchange (vPBX) services including telephony, fax, and electronic messages. In an example embodiment, the hybrid communications system  150  manages resources such as communication resources allocated to a premises. For example, hybrid communications system  150  manages telephony or wireless bandwidth resources for an office building. 
     In alternate embodiments one or more of the devices  110  can be coupled to communications system  150  through a home network and not an enterprise network  120 ,  125 . A home network is a local area network that is coupled to the hybrid communications system via the network, and in some cases a firewall. In some embodiments, the home network uses standard communications technologies and/or protocols. Thus, a home network can include links using technologies such as Ethernet, 802.11 standards, worldwide interoperability for microwave access (WiMAX), WiFi, 3G, digital subscriber line (DSL), etc. For example, device  110   a  can be coupled to a home network that is coupled to the network  130 . In this example, the device  110   a  would have an additional signaling path and session path to the hybrid communications system  150  that passes through the home network (and possibly a firewall) and the network  130 , but the additional paths would not pass through the enterprise network  120 . In embodiments using a home network, the hybrid communication system  150  operates in a manner similar to that described in the system  100  shown in  FIG. 1 , except that one or both of the enterprise networks  120 ,  125  can be replaced with a home network. 
     Turning now to a detailed discussion of the communications server  150 ,  FIG. 2  is a high-level block diagram illustrating a detailed view of modules within the hybrid communications system  150  according to an example embodiment. Some embodiments of the hybrid communications system  150  have different modules than those described here. Similarly, the functions can be distributed among the modules in a different manner than is described here. The hybrid communications system  150  is comprised of modules including a connection parameter store  210 , a media server  220 , a control server  230 , a quality of service module  240 , and a discovery module  250 . 
     The connection store  210  stores information used by the hybrid communication systems  100 . The connection store  210  can store, e.g., a connection parameter lookup table, codecs for various devices  110 , some other information used by the hybrid communication system  100 , or some combination thereof. The connection parameter lookup table maps one or more devices  110  to corresponding connection parameters. A connection parameter is information associated with a device  110  that is pertinent in establishing a hybrid media session with that device  110 . A connection parameter associated with a device  110  can be, for example, a codec version for the device  110 , access information for one or more firewalls that are traversed to communicate with the device  110 , communication parameters for a device  110 , one or more features (e.g., ability to receive audio, video, etc.) of the device  110 , connection history information for the device  110 , or some combination thereof. Communication parameters are one or more parameters relevant to communicating with a device  110 . Communication parameters can include, e.g., an external internet protocol (IP) address of a device  110 , an IP address of a wide area network (WAN) address of a router with network address translation (NAT) enabled, an external real-time transport protocol (RTP) port of the device  110 , a WAN RTP port of the router with NAT enabled, IP address of the device  110 , an origin RTP port of the device  110 , some other information relevant to communicating with device  110 , or some combination thereof. Connection history information is information describing previously established hybrid media sessions and/or media sessions that the device  110  participated in. For a given previous hybrid media sessions and/or media sessions, connection history information can include, e.g., device IDs for the devices that participated in the hybrid media session or media session, information describing what session channels were used in the hybrid media session or media session, QoS scores for session channels used in the hybrid media session or media session, or some combination thereof. 
     The media server  220  serves media to devices  110  participating in centralized media sessions. For a given centralized media session including a plurality of devices  110 , the media server  220  relays media data received from one device  110  to other devices  110  in the centralized media session. In some embodiments, the media server  220  is configured to mix multiple media data streams together into a same media data stream. Additionally, in some embodiments, the media server  220  is configured to transcode media data from one encoding format to another. 
     The control server  230  provides signaling data to devices  110  associated with hybrid media sessions via signaling channels. As discussed above, signaling data is information used to control a hybrid media session and can include, for example, data for initiating, accepting, managing, changing session channel, and terminating an associated hybrid media session. For example, the control server  230  can receive a communication from device  110   a  via a signaling channel to initiate a hybrid media session with device  110   b . The control server  230  can also use the signaling channel to accept device  110   a &#39;s initiation and invite device  110   b  to participate in a hybrid media session. Similarly, the devices  110  participating in a hybrid media session or the control server  220  can use signaling channels to terminate the hybrid media session. 
     The quality of service (QoS) module  240  estimates QoS for various media channels that are available for on-going media sessions. Devices  110   a ,  110   b  and/or  110   c  can be in an existing hybrid media session or in the process of initiating a hybrid media session. There are a plurality of session channels available to conduct a hybrid media session between the devices  110   a ,  110   b , and/or  110   c . The plurality of session channels includes a centralized session channel and one or more P2P channels. For each session channel, the QoS module  240  determines associated QoS factors. QoS factors are factors that affect QoS. QoS factors can include, for example, error rates, bandwidth, throughput, transmission delay, availability, jitter, or some combination thereof. The QoS module  240  can estimate the QoS factors using feedback from, e.g., the devices  110 , media servers (e.g., media server  409  as discussed below with regard to  FIGS. 4 ), and P2P media relay nodes (e.g., P2P media relay node as discussed below with regard to  FIG. 4 ), or any combination thereof. The feedback can be provided via RTP control protocol extended reports (RTP-XR), IETF RFC6035 (“Session Initiation Protocol Event Package for Voice Quality Reporting”), via a private reporting mechanism (e.g., attaching the Qos Factors in SIP BYE message and the response to the SIP BYE), or some other reporting mechanism. For each session channel, the QoS module  240  scores each of the determined QoS factors associated with the session channel to generate a set of factor scores for the session channel. In some embodiments, the QoS module  240  weights one or more of factor scores. For example, a factor score for bandwidth can be weighted higher than a factor score for error rate. 
     The QoS module  240  then generates a QoS score for the session channel using the factor scores. The QoS score describes an overall quality associated with a session channel. The QoS module  240  can aggregate the factor scores for each of the session channels to generate corresponding QoS scores for each of the session channels. Additionally, the QoS score for the session channel can be weighted by, e.g., session features and/or connection history information. For example, if the connection history information indicates that a P2P media session between  110   a ,  110   b  and/or  110   c  on a P2P session channel has successfully (e.g., occurred for longer than some threshold value of time) occurred in the past, the QoS module  240  increases the QoS score associated with the P2P session channel. Similarly, in some embodiments, the QoS module  240  adjusts the QoS score for a session channel based on what features the session channel provides relative to those allowed by the devices  110   a ,  110   b  and/or  110   c . For example, if devices  110   a ,  110   b  and/or  110   c  would like to have a hybrid media session that includes video, the QoS module  240  would reduce the weight of session channels that do not provide video capability. 
     The QoS module  240  selects session channels to establish hybrid media sessions between devices  110   a ,  110   b , and/or  110   c . For example, devices  110   a ,  110   b , and/or  110   c  (participating devices  110 ) can be in an existing hybrid media session or in the process of establishing a hybrid media session. The QoS module  240  selects a session channel having a highest QoS score of a plurality of session channels available to conduct a hybrid media session between the participating devices  110 . The QoS module  240  then notifies the participating devices  110  of the selected session channel via signaling channels, and instructs the control server  220  to instruct the participating devices  110  to establish a hybrid media session over the selected session channel. In some embodiments, where the hybrid media session is currently active on some session channel other than the selected session channel, the QoS module  240  instructs the control server  220  to instruct the participating devices  110  to terminate the previous session channel once the hybrid media session is established over the selected session channel. Alternatively, the QoS module  240  keeps the previous session channel open, and thus would not need to re-establish a connection along the previous session channel if at some later time the QoS module  240  determines that media data is to again be passed on the previous session channel. This allows a the hybrid communications server  150  to change established session channels without having to spend time terminating and re-establishing session channels. 
     Note that the QoS factors may not be constant, and have a tendency to vary over time. For example, a sudden load on the network may reduce the available bandwidth and hence reduce the associated factor score. To help account for the time varying nature of the QoS factors, the factor scores are generated based on data taken for a time interval. The time interval being greater than an amount of time to fully establish a new session channel (e.g., 500 ms). For example, a typical time interval can be one the order of several seconds, and in some embodiments can be as long as several minutes, or anywhere in between. Thus, the QoS score for each session channel is representative of the QoS over a time interval. This helps prevent the hybrid communications system  150  from continually switching back and forth between session channels due to sudden and brief changes in QoS factors. 
     Additionally, after a hybrid media session has been established, the QoS module  240  monitors the estimated QoS for session channels associated with the hybrid media session. The QoS module  240  monitors the estimated QoS by continuing to determine QoS scores for session channels associated with the hybrid media session. The session channels associated with the hybrid media session include the session channel that is actively being used by the devices  110  to conduct the hybrid media session as well as one or more alternate session channels. 
     The session policy server  250  verifies connection parameters using the connection parameter table. For example, in some embodiments, where the selected session channel is a P2P session channel, and it is the first time a P2P session channel has been selected for a given hybrid media session between  110   a ,  110   b  and/or  110   c , the session policy server  250  validates connection parameters using the connection parameter table in the connection parameter store  210 . For example, for a group of participating devices  110 , the session policy server  250  checks the connection parameter table to determine whether the codec versions associated with each participating device  110  is up to date. 
     The session policy server  250  updates connection parameters based on the validation. Continuing the above example, if the codec for a participating device  110  is out of date, the discovery server  230  can instruct the participating device  110  to download a current version of the codec from the connection parameter store  210  or some third party entity. Once the participating device  110  has updated its codec it notifies the session policy server  250  which then updates the connection parameter table to reflect the updated codec of the participating device  110 . In embodiments, where a device  110  is not able to upgrade its codec and other participating devices  110  have updated codecs that generally provide additional services, the session policy server  250  can instruct the other participating devices  110  to operate at a reduced capability during a hybrid media session such that the same services are available to all devices  110  that participate in the hybrid media session. 
     Additionally, in embodiments, where the validation indicates that a firewall between two devices  110  would not normally permit the selected P2P media session channel, the session policy server  250  configures the firewall to allow P2P media session channels between the two devices for at least the duration of the P2P media session. For example, the firewall  140  may allow P2P media sessions and firewall  145  may not normally allow P2P media sessions. The session policy server  250  can configure the firewall  145  to allow a P2P media session for at least the duration of the P2P media session. The session policy server  250  would then provide information used to establish a P2P connection through firewalls  140  and  145  to the devices  110   a ,  110   c.    
     In alternate embodiments, the session policy server  250  can be part of some other entity. For example, the session policy server  250  can be located at a server operating in one of the enterprise networks  120 ,  125 , or the network  130 . In these embodiments, the session policy server  250  can receive a communication from device  110   a  to initiate a hybrid media session with device  110   b . The session policy server  250  then determines using connection history information whether a P2P media session between  110   a , and  110   b  on a P2P session channel has successfully (e.g., occurred for longer than some threshold value of time) occurred in the past. If so, the session policy server  250  instructs the device  110   a  to attempt to connect to device  110   b  via the P2P session channel. 
       FIG. 3  is an interaction diagram of a process  300  for establishing a hybrid media session using a hybrid communications system  100 , according to an example embodiment. In various embodiments, the process can include different and/or additional steps than those described in conjunction with  FIG. 3 . Additionally, in some embodiments, the steps can be performed in a different order than described in conjunction with  FIG. 3 . 
     At step  302 , the hybrid communications system  150  receives from a device  110   a  over a signaling channel  165 A a request to initiate a hybrid media session with a device  110   c . The hybrid media session can be an audio and/or video media session. The request includes one or more communication parameters (e.g., an external IP address of a device  110 , an external real-time transport protocol (RTP) port of the device  110 , etc.). The hybrid communications system generates a session ID identifying the requested hybrid media session. The hybrid communications system  150  acknowledge receipt of the request to initiate the hybrid media session with a return acknowledgement message to the device  110   a  that includes the session ID. Note acknowledgements sent by entities in  FIG. 3  upon receipt of some form of data to a sending entity are omitted from  FIG. 3  to help simplify the interaction diagram. 
     The hybrid communications system  150  sends  304  a request including the session ID to join a hybrid media session to the device  110   c  over a signaling channel  165 C. The request includes some, or all of, the one or more communication parameters associated with device  110   a  and the session ID for the hybrid media session. In some embodiments, the device  110   c  prompts a user to accept/deny the request. If the user denies the request, the device  110   c  notifies the hybrid communications system  150  and no hybrid media session is established. Alternatively if the user accepts the request, the device  110   c  sends  306  an acceptance to the hybrid communications system  150  over the signaling channel  165 C. The acceptance includes one or more communication parameters associated with the device  110   c . In other embodiments, the device  110   c  automatically accepts the request to join the hybrid media session. 
     Responsive to receiving the acceptance from the device  110   c , the hybrid communications system  150  notifies  307  the device  110   a  of the acceptance via the signaling channel  165 A. The notification includes some, or all of, the one or more communication parameters associated with device  110   c.    
     The hybrid communications system  150  estimates  308  a QoS for a plurality of session channels including one or more P2P media session channels and a server-controlled session channel. As discussed above with regard to  FIG. 2 , the hybrid communications system  150  estimates the QoS factors (e.g., jitter, bandwidth, etc.) using, e.g., feedback (e.g., RTP-XR) received from the devices  110 , media servers (e.g., media server  409  as discussed below with regard to  FIGS. 4 ), and P2P media relay nodes (e.g., P2P media relay node as discussed below with regard to  FIG. 4 ), or any combination thereof. The estimated values are used to generate a QoS score for each of the session channels. In some embodiments, hybrid communications system  150  weights the QoS score for each session channel by available session features. In some embodiments, hybrid communications system  150  positively weights the QoS score for P2P session channels if the connection history information indicates that a P2P media session successfully occurred (e.g., occurred for longer than some threshold value of time) in the past. The hybrid communications system  150  then selects  310  the session channel with the highest QoS score. 
     In some embodiments, where the selected session channel is a P2P session channel and it is the first time a P2P session channel has been selected for the hybrid media session, the hybrid communications system  150  validates  312  connection parameters (e.g., codec version, access information for one or more firewalls, etc.) using a connection parameter table. The hybrid communications system  150  updates  314  connection parameters based on the validation For a given device  110 , if the validation shows one or more of the connection parameters should be updated, the hybrid communications system  150  updates the device  110  with a correct connection parameter or instructs the device  110  to obtain the updated connection parameter. For example, if the codec for  110   c  is out of date, the hybrid communications system  150  can instruct the device  110   c  to download a current version of the codec from itself or some third party entity. Once the device  110   c  has updated its codec it notifies the hybrid communications system  150  which then updates the connection parameter table to reflect the updated codec of the device  110   c . In embodiments, where a device  110   c  is not able to upgrade a codec, the hybrid communications system  150  instructs the other devices  110   a  to operate at a reduced capability during the hybrid media session such that the same services are available to all devices  110   a  and  110   c.    
     Additionally, in embodiments, where validation indicates that a firewall between two devices  110  would not normally permit P2P media session channels, the hybrid communications system  150  configures the firewall to temporarily allow P2P media session channels between the two devices for at least the duration of the hybrid media session. For example, firewall  140  may allow P2P media session and firewall  145  may not normally allow P2P media sessions. The hybrid communications system  150  can configure the firewall  145  to temporarily allow a P2P media session. The hybrid communications system  150  would then provide information used to establish a P2P connection through firewalls  140  and  145  to the devices  110   a ,  110   c.    
     Alternatively, if the hybrid media session was at some point previously established using a P2P session channel between devices  110   a  and  110   c , or the selected session channel is a centralized session channel, steps  312  and  314  are not performed, and the flow moves from step  310  to step  316 . 
     The hybrid communications system  150  notifies  316  the devices  110   a  and  110   c  of the session channel selected in step  310  via signaling channels  165 A and  165 C, respectively. In embodiments, where the selected session channel is a P2P session channel (e.g.,  160 B), the hybrid communications system  150  instructs the devices  110   a  and  110   c  to establish a P2P media session over the selected P2P session channel  106 B, such that media data is communicated on the P2P session channel  160 B. The devices  110   a  and  110   c  then establish  318  the P2P media session over the selected P2P session channel such that media is being passed between the devices  110   a  and  110   c  via the P2P media channel. The signaling of the media session is still handled via the hybrid communications system  150  via signaling channels  165 A and  165 C. 
     In embodiments, where the selected session channel is a centralized session channel, the hybrid communications system  150  establishes  320  a centralized media session with the devices  110   a  and  110   c  via centralized session channels  155 A and  155 C, respectively, such that media data is communicated via the centralized session channels  155 A and  155 C. The signaling of the hybrid media session is still handled via the hybrid communications system  150  via signaling channels  165 A and  165 C. 
     The hybrid communications system  150  monitors  322  the estimated QoS of the plurality of session channels. The QoS scores associated with one or more of the plurality of session channels can vary over time. If a different session channel has a highest QoS score for more than a threshold period of time, the hybrid communication system  150  determines that the different session channel has a highest QoS, and the interaction diagram moves to step  310 . 
     In some embodiments, once the hybrid media session is established (e.g.,  318  or  320 ) on the different session channel, the communications server  150  instructs the devices  110   a  and  110   c  continue to conduct the media session via the different session channel, but keep the previously active session channel open. The hybrid communications system  150  can then instruct devices  110   a  and  110   c  to provide data on either path in accordance with its associated QoS. This allows a hybrid media session established in the hybrid system  100  to go back and forth between session channels without having to spend time terminating and re-establishing session channels. While two session channels are discussed above, there can be more than two session channels, for example a plurality of P2P session channels and a centralized session channel. For example, at some later time a third session channel has the highest QoS, the hybrid communications system  150  instructs the participating devices  110  to establish the hybrid media session on the identified third session channel. In some embodiments, the other two session channels remain open. As the hybrid media session continues, the hybrid communications system  150  instructs the participating devices  110  to provide media data on whichever session channel has the highest QoS. This allows the hybrid communications system  150  to change established session channels during the hybrid media session without having to spend time terminating and re-establishing session channels. In other embodiments, once the new session channel is established ( 318  or  320 ), the communications server  150  terminates the prior selected session channel, and the devices  110   a  and  110   b  continue to conduct the hybrid media session via the newly established session channel. 
     The above process continues until the hybrid media session is terminated by one or more of the devices  110 . The process  300  actively selects, monitors, and possibly changes which session channel a hybrid media session is occurring over as a function of the session channel&#39;s QoS. Accordingly, the process  100  can provide the users with a hybrid media session having an average QoS that is higher than other conventional systems. 
       FIGS. 4-6  are wire diagrams explaining in detail an example process for conducting a hybrid media session using a hybrid communications system  100 .  FIG. 4  is a wire diagram of a process  400  for establishing a hybrid media session using a hybrid communications system  400 , according to an example embodiment. In various embodiments, the process can include different and/or additional steps than those described. Additionally, in some embodiments, the steps can be performed in a different order. 
     An endpoint A  402  (e.g., device  110   a ) sends F 1  an invite (also referred to as invitation) to a SBC 1  (session boarder controller)  406 . The SBC 1   406  is located at e.g., the hybrid communications system  150 . The SBC 1   406  sends F 2  an invite to a call agent  408  on the hybrid communications system  150 . The call agent  408  is located at, e.g., the hybrid communications system  105 , and handles signaling communications endpoints and receives and/or transmits signaling data via signaling channels coupled to endpoint A  402  and endpoint B  404 . The call agent  408  at step F 3  notifies the SBC 1   406  that it is received the request and needs time to handle it, and at step F 4  the SBC 1   406  provides a similar message to the endpoint A  401 . The three digit numbers indicated in steps F 3  and F 4  are SIP codes (and similarly in some other illustrated steps), which are defined by IETF RFC3261. For example, step F 3  includes a “100” which is the SIP code for “Trying.” 
     Responsive to receipt of the invite sent at F 2 , the call agent  408  initiates a new invitation based on the SIP request URI of F 2  which is based on F 1 . The call agent  408  then sends F 5  an invitation to the SBC 2   410 , which then sends F 6  an invite via a signaling channel to an endpoint B  404  (e.g., device  110   b  or device  110   c ) to join a media session. The invitation includes some, or all of, the communication parameters associated with the endpoint A  402 . Communication parameters can include, e.g., an external IP address of the endpoint A  402  (e.g., an IP address of a wide area network (WAN) address of a router with NAT enabled or an IP address of the endpoint A  402 ), an external RTP port of the endpoint A  402  (e.g., a WAN RTP port of the router with NAT enabled or an RTP port of the endpoint A  402 ), IP address of the endpoint A  402 , an origin RTP port of the endpoint A  402 , some other information relevant to communicating with endpoint A  402 , or some combination thereof. In step F 7  the SBC 2   410  is notified that the endpoint B  404  is “ringing” and that the system is waiting for the endpoint B  404  to answer the call. The SBC 2   410  replays this message at step F 8  to the call agent  408 . The call agent  408  matches the record in the servers (e.g., hybrid communications system  150 ), and creates a new  180  at step F 9  to SBC 1   406  which forwards the ringing information at step F 10  to the endpoint A  402 . In embodiments where the call agent  408  uses the 180 SIP code for F 9  and F 10 , then the Endpoint A  402  generates the ring back tone locally in the endpoint A  402 . In embodiments where the call agent  408  is using a 183 SIP code for F 9  or F 10 , then the Endpoint A  402  plays the media (e.g. greeting) from the media server  409 . 
     At steps F 11 -F 14 , the endpoint B  404  provides, via the SBC 2   410 , the call agent  408  and SBC 1   406 , some, or all of, its associated communication parameters to endpoint A  402 . Once this is complete both endpoints have the RTP information of each other and are able to establish a hybrid media session with each other. Accordingly, endpoints A and B can establish a centralized media session via, e.g., steps F 15 -F 18 . 
     In some embodiments, the endpoints can establish one or more P2P session channels in steps F 19 A that occur between the endpoints A  402  and B  404 , and are shown in detail in  FIG. 5 .  FIG. 5  is a wire diagram of a process  500  for establishing a P2P session in the hybrid communications system  400  of  FIG. 4 , according to an example embodiment. In various embodiments, the process can include different and/or additional steps than those described in conjunction with  FIG. 5 . Additionally, in some embodiments, the steps can be performed in a different order than described in conjunction with  FIG. 5 . Endpoint A  402  attempts to connect to endpoint B  404  directly using a new invite. Endpoint A  402  sends at F 19 . 1  an invite to the external IP address of the endpoint (can be WAN IP address of the router with NAT enabled) and the external RTP port (can be WAN RTP port of the router with NAT enabled) of endpoint B  404 , and sends at F 19 . 2  an invite to the IP address and to the origin RTP port of endpoint B  404 . If the invite from step F 19 . 1  is received, the endpoint B  404  sends an acknowledgement at F 19 . 3 , and if the invite from step F 19 . 2  is received, the endpoint B  404  sends an acknowledgement at F 19 . 4 . A P2P media session can be established if endpoint A  402  receives at least one of the acknowledgements. 
     Concurrent with establishing a P2P session channel directly between the endpoints A  402  and B  404 , the endpoints attempt to establish a session channel over a P2P media relay node  412  as shown in steps F 19 B and F 19 C in  FIG. 4 , and is shown in detail in  FIG. 6 .  FIG. 6  is a wire diagram of a process  600  for establishing a P2P session channel between endpoints A and B via a P2P media relay node  412  in the hybrid communications system  400  of  FIG. 4 , according to an example embodiment. In various embodiments, the process can include different and/or additional steps than those described in conjunction with  FIG. 6 . Additionally, in some embodiments, the steps can be performed in a different order than described in conjunction with  FIG. 6 . 
     The endpoint A  402  sends an invite at step F 19 . 5  to the P2P media relay node  412  that includes a session ID. The P2P media relay node  412  replaces the IP address in the invitation from endpoint A  402 , including the IP address and the transport port for the SIP response to come back and the IP address and the transport port to receive the media from the endpoint B  404 . The P2P media relay node  412  forwards the modified invitation at step F 19 . 6  to the endpoint B  404 . The endpoint B  404  sends at step F 19 . 7  an OK of the received modified invitation to endpoint A  402 , and an RTP connection between the P2P media relay node  412  and endpoint A  402  is established. Heartbeat messages can be exchanged between the endpoint A  402  and the P2P Media Relay Node  412 , and similarly heartbeat messages can be exchanged between the endpoint B  404  and the P2P media relay node  412 . In general, a heartbeat message is a message that enables an endpoint to identify if and when the other endpoint fails or is no longer available. The F 19 . 5 -F 19 . 8  messages are special heartbeat messages, which can be used to set up a media relay between the endpoint A  402  and the endpoint B  404 . Additional heartbeat messages can be used to keep the link alive between P2P media relay  412  and the endpoint A  402  and the endpoint B  404 . 
     The P2P media relay node  412  modifies a signaling data path of the invite with a RTP port created in the P2P media relay node  412  and the IP address of the P2P media relay node  412 , and then sends at step F 19 . 6  the modified invite to the endpoint B  404 . In embodiments, where endpoint B  404  is not able to create an additional P2P session channel, endpoint B  404  rejects the modified invite. Alternatively, in embodiments where endpoint B  404  is able to create an additional P2P session channel, the endpoint B  404  accepts the modified invite and sends an OK at step F 19 . 7 . The P2P media relay node  412  modifies the SDP of the OK from endpoint B  404  with a RTP port created in the P2P media relay node  412  and the IP address of the P2P media relay node  412 , and then forwards at F 19 . 8  the modified OK to endpoint A  402 . The P2P media relay node  412  then acts as a packet relay for data passed from endpoint A  402  to endpoint B  404 , and versa. 
     Turning back to  FIG. 4 , the endpoints A  402  and B  404  report at F 20 A and F 20 B some QoS factors to a P2P media policy server  414  (e.g., hybrid communications system  150 ). Additionally, at F 21  the P2P media relay node  412  provides F 21  additional QoS factors to the P2P media policy server. In some embodiments, the QoS factors are provided periodically (e.g., every few seconds, few minutes, etc.). Alternatively, the QoS factors can be provided if one or more fall below some threshold value. In some embodiments, the QoS factors are provided via, e.g., RTP-XR, IETF RFC6035, etc. In embodiments (e.g., where several media paths are being merged into a single media path) the QoS factors also includes overall voice quality. The QoS factors can also describe which endpoints are contributing to playback (e.g., which are providing audio input versus which are silent). As described above with regard to  FIGS. 2 and 3 , the hybrid communications system  150  uses the QoS factors to determine a QoS for each session channel, and add, switch, terminate, or pause one or more session channels. 
     The SBC 1   406  and SBC 2   410  assist endpoint A  402  and endpoint B  404  finish the NAT transversal. In current industry implementation, all of the call control (e.g. SIP messages) goes through a SBC to reach a call agent, and the SBC removes the session description protocol (SDP) in an invite that is received from end points, and constructs a new SDP to replace the old SDP. The SDP contains the IP address, the media UDP port and the media codec of the end points. In this manner, the current industry implementation ensures that a media session from/to the end points can go through respective SBCs to reach a media server. 
     The SBC 1   406  and SBC 2   410  in the hybrid communications system  400  can operate as conventional systems, however, they also can keep the old SDP—which differs from the conventional system described above. Keeping the old SDP ensures the original SDP in the INVITE of the endpoint A  402  and endpoint B  404  are visible to each other (and potentially other endpoints) so that they can conduct a P2P media session. In some embodiments, the SBC 1   406  and SBC 2   410  modify the INVITE messages, including headers and SDP, but do not handle the call logic (or call control). In alternate embodiments, the hybrid communications server  150  can make the original SDP of the endpoint A  402  and endpoint B  404  visible to each other (and potentially other endpoints) using e.g., session traversal utilities for NAT (STUN), traversal using relay NAT (TURN), interactive connectivity establishment (ICE), or some other method. 
       FIG. 7  is a high-level block diagram illustrating an example computer  700  for implementing the entities shown in  FIG. 1 . The computer  700  includes at least one processor  702  coupled to a chipset  704 . The chipset  704  includes a memory controller hub  720  and an input/output (I/O) controller hub  722 . A memory  706  and a graphics adapter  712  are coupled to the memory controller hub  720 , and a display  718  is coupled to the graphics adapter  712 . A storage device  708 , input interface  714 , and network adapter  716  are coupled to the I/O controller hub  722 . Other embodiments of the computer  700  have different architectures. 
     The storage device  708  is a non-transitory computer-readable storage medium such as a hard drive, compact disk read-only memory (CD-ROM), DVD, or a solid-state memory device. The memory  706  holds instructions and data used by the processor  702 . The input interface  714  is a touch-screen interface, a mouse, track ball, or other type of pointing device, a keyboard, or some combination thereof, and is used to input data into the computer  700 . In some embodiments, the computer  700  can be configured to receive input (e.g., commands) from the input interface  714  via gestures from the user. The graphics adapter  712  displays images and other information on the display  718 . The network adapter  716  couples the computer  700  to one or more computer networks. 
     The computer  700  is adapted to execute computer program modules for providing functionality described herein. As used herein, the term “module” refers to computer program logic used to provide the specified functionality. Thus, a module can be implemented in hardware, firmware, and/or software. In one embodiment, program modules are stored on the storage device  708 , loaded into the memory  706 , and executed by the processor  702 . 
     The types of computers  700  used by the entities of  FIG. 1  can vary depending upon the embodiment and the processing power required by the entity. For example, the hybrid communications system  150  might comprise multiple blade servers working together to provide the functionality described herein. The computers  700  can lack some of the components described above, such as keyboards, graphics adapters  712 , and displays  718 . 
     Additional Configuration Information 
     The foregoing description of the embodiments has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the patent rights to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. 
     Some portions of this description describe the embodiments in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. 
     Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. 
     Embodiments may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
     Embodiments may also relate to a product that is produced by a computing process described herein. Such a product may comprise information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein. 
     Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the patent rights be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments is intended to be illustrative, but not limiting, of the scope of the patent rights, which is set forth in the following.