Patent Grant
8473617
Cellular telephone networks were originally developed to provide primarily voice services over circuit-switched networks. Although circuit-switched networks are still in widespread use, the current trend is toward packet switched networks that provide not only voice services, but also high-speed packet data services, that enable mobile users to surf the web, read email, download video and audio files, and do many other things that Internet users can do on fixed networks. However, real-time multimedia remains a problem in mobile networks because most packet data services are provided by best effort networks that lack quality of service guarantees needed for real-time multimedia services. Also, due to lack of standardization, network operators are often limited to offering only those IP services that their equipment vendors support. Lack of standardization also makes it difficult for network operators to purchase bundled services from third party developers.
The IP multimedia subsystem (IMS) was developed to provide a common, standardized architecture and standardized interfaces for providing IP services in a mobile networking environment. The IMS network is not dependent on the access technology and will interoperate with virtually any packet-switched network, including UMTS, cdma2000, GPRS and EDGE networks. IMS uses the session initiation protocol (SIP) as the service control protocol, which allows operators to offer multiple applications simultaneously. The IMS standard will speed the adoption of IP services on mobile terminals, allowing users to communicate via voice, video, or text using a single client on the mobile terminal.
Although IMS promises a richer experience to mobile subscribers, network operators are hesitant to invest in equipment to implement IMS until there are a sufficient number of subscribers with IMS capability to make the investment worthwhile. Most cellular telephones currently in use lack IMS capabilities, so the pool of potential subscribers for IMS services is relatively small. Extending IMS capabilities to legacy mobile terminals that lack inherent IMS capabilities would provide a much broader market for network operators and encourage investment in IMS technology and equipment.
The present invention relates to a network-centric media client that provides SIP and/or IMS capabilities to mobile terminal users. The media client may be incorporated within the mobile terminal, or may be located in a mobile network and accessed remotely by the mobile terminal. The remote access capability allows IMS services to be provided to legacy mobile terminals that lack inherent IMS capabilities.
The media client includes a user agent that communicates with a multimedia application over a first network interface, a signaling agent that communicates with the user agent over a second network interface, and a media agent that communicates with the user agent over a third network interface. The network interfaces enable local and/or remote access. The user agent provides a high-level application interface to the multimedia application that insulates the multimedia application from the details of the underlying network protocols. The media client may also include a JAVA application interface. The signaling agent operates under the direction of the user agent and performs signaling tasks necessary for establishing, modifying, and terminating communication sessions for media transfers. The media agent operates under the control of the user agent and performs media operations, such as managing media connections and routing media to appropriate rendering devices. The user agent, signaling agent, and media agent may be co-located within the network or may be distributed among network components.
The present invention is also applicable to fixed networked communication devices, such as DVD and CD players, digital video recorders, video cameras, digital still cameras, scanners, home stereo systems, television systems and computers, to enable media sessions between networked communication devices via a communication network. The present invention may also be used to remotely control a networked communication device.
The mobile communication network 10 comprises a radio access network (RAN) 20, a core network (CN) 30, and an IP Multimedia Subsystem (IMS) 40. The RAN 20 supports radio communications with mobile terminals 100 over an air interface. A mobile terminal 100 is a networked communication device as that term is used herein. The mobile communication network 10 typically includes more than one RAN 20 though only one is shown in
The IMS 40 uses open interfaces and an access independent session control protocol (SCP), such as the Session Initiation Protocol (SIP), to support multi-media applications. Session description protocol (SDP) is used for media negotiation. SDP is described in IETF RFCs 2327 and 3264. SIP is a session control protocol for establishing, modifying and terminating communication sessions between one or more participants. These sessions may include, for example, Internet multimedia conferences, Internet telephony calls, and multimedia distributions. SIP is described in the IETF document RFC 3261. While a preferred embodiment of the invention as described herein uses the SIP, those skilled in the art will appreciate that the present invention may use other SCPs as well. Another well-known protocol comparable to the SIP is H.323. The details of the SIP are not material to the present invention, but a brief overview of the SIP is given below to better place the invention in context.
SIP is a signaling protocol that uses ASCII-based signaling messages to establish a communication session between two or more participants. Users are identified by a unique address referred to herein as the SIP address. Users register with a registrar server using their assigned SIP addresses. The registrar server provides this address to a location server upon request.
When a user initiates a call, a SIP request is sent to a SIP server (either a proxy server or a redirect server). The request includes the calling party address and called party address in a message header. If a proxy server receives the SIP request, it forwards the SIP request to the called party. The called party may be another user or may be an application server in the user's home network. The called party responds to the proxy server, which in turn, forwards the response to the calling party. The calling party acknowledges the response and a session is then established between the calling party and the called party. Real-time Transfer Protocol (RTP) described in IETF RFC or the Message Session Relay Protocol (MSRP) described in IETF RFC is used for the communication between the calling party and the called party.
If a redirect server receives the SIP request, the redirect server contacts the location server to determine the path to the called party, and then sends that information to the calling party. The calling party acknowledges receipt of the information and then resends the SIP request to the server identified in the redirection information (which could be the called party of a proxy server). When the SIP request reaches the called party, the called party responds and the calling party acknowledges the response. Communications then begin using RTP or MSRP. SIP is used only to process signaling messages related to call control and session management.
As described above, SIP enables applications within the mobile communication network 10 to establish a communications session. The applications may reside in a mobile terminal 100 or in an application server in the IMS 40. Additionally, the applications may reside in different networks 10.
The present invention provides a media client 200 shown in
In some realizations, a monolithic approach may be taken, integrating the UA 202, SA 204, and MA 206 together in a single application. In the embodiment shown in
The distributed approach has several advantages over the monolithic approach. The media client 200 may be located in a network server in the IMS 40 or other IP network and remotely accessed by a mobile terminal 100 using, for example, telnet to open a socket connection. Thus, IMS services can be provided to mobile terminals 100 that do not have inherent IMS capabilities. The separation of the UA 202, SA 204, and MA 206 allow these elements to be distributed within the network 10 so that the UA 202, SA 204, and MA 206 can reside in different locations within the network 10. By locating the media client 200 in a network with low bandwidth or high latency, improved performance may be realized because the high level API for the media client 200 reduces the amount of signaling over the air interface. Further, the SA 204 and MA 206, which generate the majority of the signaling, can be located closer to the network backbone. The separation of the SA 204 and MA 206 also allows for optimized implementations of stand-alone media (e.g., TV) and control (e.g., remote control) devices.
The media client 200 is implemented as a process running on a host device, such as a PC or mobile terminal 100. The host device includes memory in which to store code implementing the present invention, one or more microprocessors to execute the code, and a communications interface providing network access. The UA 202, SA 204, and MA 206 may reside in different hosts. After it boots up, the media client 200 opens a server socket on a designated port, e.g., port 3500 for communications between the UA 202 and the user application 150. Any user application 150 wishing to communicate with the media client 200 can open a client socket on the same port. The port for communications between the UA 202 and the user application 150 may be specified in a configuration file. Different ports may be opened for communications between the UA 202 and the SA 204, or between the UA 202 and MA 206.
In one exemplary embodiment, the media client 200 uses a text-based interface protocol (the UA API) for communications between the user application 150 and the media client 200. All communications between the user application 150 and media client 200 are by text strings read and written to the TCP socket. The IMS protocol uses two types of messages for communications—requests and responses. The user application 150 typically sends requests to the UA 202 to initiate a transaction, though the UA 202 can also send requests to the user application 150. Requests typically have parameters, which are separated by spaces. The UA 202 typically sends responses to the client in response to requests. There are two kinds of responses, provisional and final. Provisional responses do not end the transaction initiated by the corresponding request. Final responses terminate the transaction.
The application interface between the UA 202 and the SA 204 (the SA API) and the application interface between the UA 202 and the MA 206 (the MA API) also use text-based interface protocols similar to the UA API. Requests from the UA 202 requiring action by either the SA 204 or the MA 206 start a transaction between the UA 202 and the SA 204 or MA 206. Table 1 in Appendix A documents exemplary requests and responses for the UA API. Table 2 in Appendix B documents exemplary requests and responses for the SA API. Table 3 in Appendix C documents exemplary requests and responses for the MA API.
The main requests in the UA API are the REGISTER request, the CALL request, the MSG request, the ACCEPT request, the HANG-UP request, the SUBSCRIBE request, the NOTIFY event, and the PUBLISH request. The REGISTER request, SUBSCRIBE request, NOTIFY request and PUBLISH request correspond to standard SIP requests, but provide a higher level of abstraction for the user application 150.
The REGISTER request is sent by the user application 150 to the media client 200 to register with a SIP registrar. A typical REGISTER request is in the form “register aol.com” or “register msn.com: 5050.” In response to the REGISTER request, the UA 202 instructs the SA 204 to perform a SIP registration. After registering with the SIP registrar, the SA 204 sends a message to the UA 202 indicating the status of the registration attempt, e.g., successful or failed. An exemplary REGISTER response is “register 200:OK” if the registration is successful, and “register 1xx:failed” if the registration is not successful.
The CALL request is sent by the user application 150 to the UA 202 to connect with a remote device. The CALL request is used to initiate a RTP or MSRP session. The CALL request includes information identifying the called party and the call type, such as a user ID, alias, or fully qualified network address. If a proxy is involved, the CALL request may specify the user ID of the called party. If a proxy is not involved, the CALL request may give the fully qualified address and port of the remote host to connect to. The call type may comprise, for example, the mime type and sub-type, e.g. video/h263 or audio/amr. The CALL request typically takes the form “call alice video/h263” or “call alice@ims.net: 5060 video/h263” or “call 10.0.0.1:5060 video/h263.” More than one call type may be included in a single CALL request. Depending on the outcome of the CALL request, the UA 202 sends a CALL response indicating the outcome or status of the CALL request. An exemplary CALL response is “call connected” if the connection is “successfully established” or “call failed” if the connection was not successful. The CALL response may optionally include a status code providing additional information, such as an error code indicating why call request was unsuccessful. If the connection succeeds, the user application 150 can begin sending and receiving media and/or messages over the RTP or MSRP connection.
A CALL request may also be sent by the UA 202 to the user application 150 in the case of an incoming call. In this case, the CALL request includes information identifying the calling party rather than the called party. Otherwise, the CALL request is the same. The information identifying the calling party may comprise a user ID of the called party or a fully qualified address for a remote host. When a CALL request is sent from the UA 202 to the user application 150, the user application 150 does not send a CALL response. Instead, the user application 150 sends an ACCEPT request that terminates the CALL request.
The ACCEPT request is sent by the user application 150 responsive to a CALL request to instruct the UA 202 to either accept or reject an incoming call. The ACCEPT request includes a command indicating that the UA 202 should either accept or reject the call and optionally a code indicating, for example, why a call is rejected. If more than one call type is specified in the CALL request, the user application 150 may accept a subset and reject the rest. To accept less than all of the specified call types, the user application includes a list of the accepted call types in the ACCEPT request. The UA 202 should accept those listed and reject the rest. If no call type is specified in the ACCEPT request, the UA 202 by default may accept all call types specified in the CALL request. A typical ACCEPT request is in the form “accept yes” to accept the call or “accept no” to reject the call. If less than all specified call types are accepted, the ACCEPT request has the form “accept OK audio/amr”, which specifies the accepted call types.
Depending on whether the connection is successfully made, the UA 202 sends an ACCEPT response to the user application 150. The ACCEPT response includes a status message indicating whether the connection was successfully made and optionally a status code. A typical ACCEPT response has the form “accept OK” or “ACCEPT Failed:1xx.”
The MSG request is sent by the user application 150 to the media client 200 to request transmission of messages. The MSG request includes a call ID or session ID identifying the call in which the message is to be sent, the message length, the message type, and the message data. For text messages, the MSG request is of the form “msg xxx nnn text/plain\n this is the text” where xxx is the call ID or session ID and nnn is the length of the text only (not including the new line or header). The new line character separates the message type from the message data. An example of a text message sent using the MSG request is “msg 111 5 text/plain\n hello.” For binary data, the MSG request is of the form “msg xxx nnn mime/type\n” where xxx is the call ID and nnn is the length of the data buffer. An example of a binary message is “msg 111 43 image/jpg\n31290759 . . . 93285.” The UA 202 sends a MSG response to the user application 150 to indicate successful delivery or failure of the MSG request. An exemplary MSG response is in the form “MSG OK,” if the message is successfully delivered and “MSG Failed:1xx” if the message is not successfully delivered.
The HANGUP request is used to terminate a connection. The HANGUP request can be sent by the user application 150 to the media client 200 or vice versa. The HANGUP request may comprise the single term “hang-up” or single letter “h” and the call ID assigned to the call being ended. An exemplary HANGUP request is in the form “hangup xxx” where xxx is the call ID. When the HANGUP request is sent by the user application 150 to the UA 202, the UA 202 sends a HANGUP response to confirm that the call is ended. The HANGUP response may be in the form “hangup OK” or “hangup disconnected.”
The SUBSCRIBE request is sent by the user application 150 to the UA 202 to subscribe to a presence service or other notification service. The SUBSCRIBE request includes an address for the subscription service, the expiration time for the subscribe request, and the event to which the subscribe request pertains. The typical form of the SUBSCRIBE request is “subscribe someone@domain.com:3600 ttt presence” or “subscribe someone at his domain.com:3600 ttt presence autofresh” where m represents the expiration time in seconds of the subscribe request. In response to the SUBSCRIBE request, the UA 202 instructs the SA 204 to perform a SIP subscription procedure. After the SIP subscription procedure is successfully completed, the SA 204 notifies the UA 202, which in turn notifies the user application 150 by sending a SUBSCRIBE response. The SUBSCRIBE response includes an address for the subscription service, the expiration time in seconds of the subscription, and a status message. The expiration time may be different than requested. The SUBSCRIBE request may optionally include a status code and an “autorefresh” command to automatically refresh the SUBSCRIBE request when it expires. It is possible for the SUBSCRIBE request to fail because of a redirect request. In this case, the SUBSCRIBE response may return a new address and the UA 202 may re-subscribe using the new address. The SUBSCRIBE response is in the form “subscribe ttt me@mydomain.com:3600 successful:200” if the subscription is successfully executed and “subscribe ttt me@mydomain.com 3600 failed:481” if the subscription fails.
The NOTIFY request is sent from the UA 202 to the user application 150 to notify the user application 150 of a change in the presence status of a presence entity giving presence notification to the user application 150. The NOTIFY request includes the message size, the type of event that triggered the NOTIFY, the mime type of the message body, and the message data. The typical form of the NOTIFY request is “notify 30 someone@hisdomain.com presence application/pidf+xml\alice is now available.” The user application 150 responds with “Notify OK” to acknowledge the NOTIFY request.
The PUBLISH request is used for presence services and other notification services. The PUBLISH request is sent by the user application 150 to the media client 200 to notify the presence server when the presence state of the user changes. The PUBLISH request includes the address of the presence server and the expiration time for the PUBLISH request. The PUBLISH request may optionally include an “autorefresh” command to automatically refresh the PUBLISH request when it expires. A typical PUBLISH request takes the form “publish ttt me@mydomain.com 3600.” The UA 202 responds to the user application 150 with “publish ttt me@mydomain.com 3600 successful:200” if the publication is successful and with “publish ttt me@mydomain.com 3600 failed:481” if the publication fails.
Table 2 in Appendix B describes requests and responses used in the SA API. The main requests include the REGISTER request, the INVITE request, the ACK request, the SUBSCRIBE request, the NOTIFY request, the PUBLISH request, and the BYE request, which correspond to standard SIP requests. The REGISTER request is used to register with a SIP registrar. The INVITE and ACK requests are used to establish a SIP session. The SUBSCRIBE, NOTIFY and PUBLISH requests are used to implement presence services or other notification services. The BYE request is used to terminate a SIP session. Some requests used in the SA API correspond to common SIP requests and use the same names. It should be apparent from the context which request is being referred to. However, to avoid confusion, the prefix SIP is used to identify standard SIP requests and responses sent to/from the SA 204.
The REGISTER request is sent from the UA 202 to the SA 204 responsive to a corresponding REGISTER request from the user application 150. The REGISTER request includes the network address and optionally a port of the SIP registrar or a SIP proxy. The REGISTER request is in the form “register server@network.com.” The SA 204, responsive to the REGISTER request, attempts registration with a SIP registrar according to SIP as described in IETF RFC 3261. The SA 204 sends a REGISTER response to the UA 202 indicating the status of the REGISTER request. An exemplary REGISTER response is in the form “register OK” if the registration attempt is successful, or “register failed” if the registration attempt is unsuccessful.
The INVITE request is sent by the UA 202 to the SA 204 responsive to a CALL request from the user application 150 at the originating end of a call. The SA INVITE request includes the address of the called party or a user ID that can be resolved to a valid address, the call type specifying the type of call to be established, and the host address used for the media session for each call type specified. The same host address may be used for each call type or different addresses may be used. An exemplary INVITE request is in the form “invite alice@domain.com video/h263 me@mydomain.com:xxx audio/amr me@mydomain.com:xxx, where xxx indicates port number. After sending the INVITE request, the UA 202 waits for a response from the SA 204. The SA 204, responsive to the INVITE request, sends a SIP INVITE request to the called party specified in the INVITE request and waits for a response. If a connection is successfully established, the SA 204 sends an INVITE response to the UA 202 indicating that the invitation is accepted. The INVITE response includes a session identifier, referred to herein as the call ID.
An INVITE request may also be sent by the SA 204 to the UA 202 responsive to receipt of a SIP INVITE at the receiving end of a call. In this case, the INVITE request includes the address of the calling party used for signaling, and the address or addresses used by the calling party for the media session. The INVITE response from the UA 202 to the SA 204 is the same as described above, except that the session identifier is not included. In this case, the session identifier is sent in an ACK request from the SA 204 to the UA 202 after the SA 204 receives a SIP ACK from the calling party.
The SUBSCRIBE request is sent by the UA 202 to the SA 204 to initiate subscription to a presence service or other notification service. The SUBSCRIBE request includes the address of the party from which the user wants to receive presence state information or of a presence server. The SA 204, upon receipt of the SUBSCRIBE request from the UA 202, sends a SIP SUBSCRIBE request to the host designated in the SA SUBSCRIBE request and waits for a response. The host to whom the SIP SUBSCRIBE request is sent returns a SIP NOTIFY request to the SA 204. The SIP NOTIFY request indicates whether the SIP SUBSCRIBE request was authorized, and, if so, includes the current presence state information. The SA 204 acknowledges the SIP NOTIFY request and sends a NOTIFY request to the UA 202 containing the presence state information of the presence agent. Until the subscription expires, the presence agent who authorized the subscription sends a SIP NOTIFY request each time the presence state information changes, and the SA 204 sends a corresponding NOTIFY request to the UA 202 to forward the presence information to the UA 202.
The PUBLISH request is sent by the UA 202 to the SA 204 to notify the presence server when there is a change in the presence state of the user. If the SA 204 is functioning as a presence server, the SA 204 sends a NOTIFY request to its subscribers to notify the subscribers of the change in presence state. If a separate presence server is used to distribute presence information, the SA 204 sends a corresponding SIP PUBLISH request to the presence server. After sending the SIP PUBLISH request, the SA 204 sends a PUBLISH response to the UA 202 indicating the status of the PUBLISH request.
The BYE request is sent by the UA 202 to the SA 204 or vice versa to terminate a SIP session. When the SA 204 receives the BYE request from the UA 204, it sends a SIP BYE request to the other party to terminate the session. Once the SIP BYE request is acknowledged, the SA 204 sends a BYE response to the UA 202 to acknowledge the BYE request. When the UA 202 receives a BYE request from the SA 204, it closes the connection opened for the call specified in the BYE request. In this case, no response to the BYE request is required because the BYE request is mandatory.
Table 3 in Appendix C describes the MA API. The main request in the MA API include the LISTEN request, the CONNECT request, the SEND request, the OPEN request, the PEER request, and the CLOSE request.
The LISTEN request is sent by the UA 202 to the MA 206 to initiate an MSRP session for multimedia messaging. The UA 202 sends the LISTEN request in response to a call request from the user application 150 requesting an MSRP session. The LISTEN request may optionally include the address of a remote host from which connections can be made. When the remote host is specified in the LISTEN request, connections will be accepted only from the specified host. In response to the LISTEN request, the MA 206 opens a port for a media connection and sends a LISTEN response to the UA 202 giving the address and port for the media connection.
The CONNECT request is sent by the UA 202 at the receiving end of a call to the MA 206 to establish a MSRP connection. The CONNECT request is typically sent after the user at the receiving end of a call accepts an invitation from the calling party to join a call. The CONNECT request includes the network address and port specified by the calling party in the SIP INVITE. An exemplary CONNECT request is in the form “connect anybody@domain.com.” In response to the CONNECT request, the MA 206 establishes a connection according to MSRP and sends a CONNECT response to the UA 202. The CONNECT response includes the status of the CONNECT request and optionally a status code. An exemplary CONNECT response is in the form “connect OK” or “connect failed.”
The SEND request is used to send multimedia messages once a MSRP session is established. When the UA 202 receives a MSG request from the media client 200, the UA 202 generates and sends a SEND request to the MA 206. The SEND request includes a call ID that uniquely identifies the call in which the message is being sent, the message length, the message type and the message data. An exemplary SEND request is in the form “send xxx nnn text/plain\n this is the text.” The MA 206 in turn sends the message according to the MSRP. When the message is acknowledged, the MA 206 sends a SEND response to the UA 202 identifying the call and indicating the status of the SEND request. The SEND request may optionally include a status code. An exemplary SEND response is in the form “send xxx OK” indicating successful delivery or “send xxx failed” indicating that the message was not successfully delivered.
The OPEN request is used to initiate an RTP session. The UA 202 sends an OPEN request to the MA 206 responsive to an ACCEPT request from the user application 150. The OPEN request optionally includes a network address of a remote host from which media connections will be accepted. If the remote host address is include in the OPEN request, media connections will be accepted only from the address specified in the OPEN request. In response to the OPEN request, the MA 206 opens a port for a media connection and returns an OPEN response indicating the network address and port for the media connection. The OPEN response indicates the status of the OPEN request and, if successful, includes the network address of the host and port opened for the RTP connection.
Once the media connection is established, the UA 202 at the originating end of a call sends a PEER request to the MA 206 to provide the MA 206 with the host address and port opened for the RTP session at other end. The only parameter for the PEER request is the network address and port for the media connection. No response to the PEER address request is required. An exemplary PEER request is in the form “peer someone@domain.com.”
The CLOSE request is used to terminate a media connection used for either RTP or MSRP sessions. The UA 202 sends the CLOSE request to the MA 206 responsive to a HANG-UP request from the user application 150.
The UA, SA and MA APIs may also have a SET request to enable certain parameters to be pre-configured during initialization. The SET request includes the parameter name and the value assigned to the named parameter. The SET request can be used to configure user-specific settings such as a username, alias, contact address, and default sources and sinks for different media.
The present invention insulates the user applications at endpoints A and B from the details of the MSRP, SIP, and SDP, which are handled by the UA 202, SA 204 and MA 206 as shown in
The SA 204 uses conventional SIP signaling to establish the MSRP session. The SA 204 constructs a SIP INVITE request from the information it receives from the UA 202 augmenting this information with default settings as required for a complete SIP INVITE request. The SA 204 sends the SIP INVITE request (e) to endpoint B. The SIP INVITE request includes an SDP (Session Description Protocol) body to describe the multimedia session. While waiting for a response from the SA 204 at endpoint B, the SA 204 at endpoint A may receive a provisional SIP response (“100 trying”)(f) from the network indicating that the network is attempting to establish a connection with endpoint B.
Once the SIP INVITE request is received by the SA 204 at endpoint B, it sends a SA INVITE request to the UA 202 (h) and may send a provisional response (g) to the SA 204 at endpoint A indicating that the SA 204 is “ringing” the user at endpoint B. The SA 204 at endpoint A, in turn, may send provisional STATUS response (k) to the UA 202 to provide a ring indication to the UA 202 at endpoint A. The UA 202 at endpoint A may, in some applications, provide the provisional status information to the user application 150 (l) to notify the user that an attempt is being made to reach the user at endpoint B.
Responsive to the INVITE request, the UA 202 at endpoint B sends a CALL request (i) to the user application 150 to notify the user application 150 that an invitation to a MSRP session was received. The CALL request includes information that identifies the calling party and the type of call. The user application 150 sends an ACCEPT request (j) in reply to the CALL request indicating whether the user wishes to answer the call. In this example, the user at endpoint B accepts the invitation. If the call involves more than one type of media, the user at endpoint B specifies which media to accept in the ACCEPT request. The UA 202 at endpoint B then sends a CONNECT request (m) to the MA 206 to open a media connection, e.g. TCP connection. The MA 206 at endpoint B sends an MSRP VISIT message (n) to the MA 206 at endpoint A to establish a MSRP connection. The MA 206 at endpoint A sends a positive response (MSRP 200 OK) to the MSRP VISIT to establish a MSRP connection between endpoints A and B (o). After the media connection is established, the MA 206 at endpoint B sends a CONNECT response (Connect 200 OK) to the UA 202 at endpoint B to indicate that a media connection was successfully established (p).
At this point the SIP INVITE request has not been accepted. The UA 202 at endpoint B sends a SA INVITE response (INVITE 200 OK) to the SA 204 at endpoint B indicating that the SA 204 should accept the invitation to join the MSRP session with endpoint A (q). The SA 204 at endpoint B sends a SIP INVITE response (SIP 200 OK+SDP body) to the SA 204 at endpoint A (r). The SIP INVITE response includes an SDP body confirming the MSRP session parameters. The SIP INVITE response is the answer to the SIP INVITE request at step (e) and contains the network address and port used by endpoint B for the media connection. The SA 204 at endpoint A acknowledges the SIP 200 OK response to complete the SIP handshake (s). At endpoint A, the SA 204 sends an SA INVITE response (t) indicating that the connection requested at step (a) was successfully established. This message includes a call identifier that uniquely identifies the call, and the network address of the host and port at endpoint B used for the media connection. The UA 202 at endpoint A in turn sends a CALL response (u) to the user application 150 indicating that the connection requested at step (a) was successfully established. At endpoint B, the SA 204 sends an ACK request (v) to the UA 202 responsive to the SIP ACK indicating that the connection with endpoint A was successful and including a SIP session identifier. The UA 202 in turn sends an ACCEPT response (w) to the user application 150 indicating establishment of a connection with endpoint A. The endpoints A and B can now begin sending and receiving messages.
The user application at endpoint A generates a multimedia message, which is passed to the UA 202 in a MSG request (x). The MSG request includes information identifying the session, the message type and the message size. The UA 202 constructs and forwards a SEND request (y) to the MA 206 with the parameters specified in the MSG request directing the MA 206 to forward the multimedia message to endpoint B. The MA 206 uses the MSRP protocol to deliver multimedia messages. The MA 206 generates a MSRP SEND request (z), supplying default parameters as need for a complete MSRP SEND request, and send the request to the MA 206 at endpoint B. The MA 206 at endpoint B extracts the message content from the MSRP SEND request and delivers the message to the UA 202 at endpoint B inside a MA SEND request (aa). The UA 202 at endpoint B uses the MSG request to forward the message content to the user application 150 (bb). The user application 150 at endpoint B acknowledges receipt of the message by sending a MSG response (MSG 200 OK) (cc) and the UA 202 in turns forwards a SEND response (dd) to the MA 206 indicating that the message was successfully delivered. The MA 206 sends an MSRP OK response (MSRP 200 OK) to acknowledge receipt of the message (ee). The MA 206 at endpoint A may optionally translate and forward the MSRP response (MA SEND 200 OK) to the UA 202 at endpoint A (ff), which in turn may optionally send a MSG response (MSG 200 OK) to the user application 150 at endpoint A indicating that the message was successfully delivered (gg).
To end the session, the user application 150 at endpoint A sends a HANG-UP request to its UA 202 (hh). Endpoint B could also end the session in the same manner. The UA 202 at endpoint A sends a SA BYE request (ii) to the SA 204 at endpoint B indicating that the call specified in the request should be ended. The SA 204 generates a SIP BYE request (r) based on the SIP session parameters established at step and sends this message to endpoint B. The SA 204 at endpoint B receives the SIP BYE request and replies to acknowledge receipt of the message (kk). At endpoint A, the SA 204 sends a BYE response (ll) to the UA 202 confirming that the media session is closed. The UA 202 sends a HANGUP response (mm) to the user application 150 to notify the user application 150 that the media session is closed, and sends a CLOSE request (nn) to the MA 206 to close the connection opened for the media session. The SA 204 at endpoint B generates a BYE request and forwards the BYE request to the UA 202 (oo) indicating that the MSRP session has been closed. Similarly, the UA 202 at endpoint B sends a HANGUP request (pp) to the user application 150 to notify the user application that the MSRP session is closed, and sends a CLOSE request to the MA 206 to close connection opened for the media session (qq).
The SA 204 uses conventional SIP signaling to establish the communication session with endpoint B. The SA 204 sends a SIP INVITE request to endpoint B (e). The SIP INVITE request includes an SDP body to describe the multimedia session. The SDP body describes the media comprising the session and codec parameters. While waiting for a response from the SA 204 at endpoint B, the SA 204 at endpoint A may receive a provisional response (f) from the network indicating that the network is attempting to establish a connection with endpoint B.
Once the SIP INVITE request is received by the SA 204 at endpoint B, it sends a SA INVITE request to the UA 202 (h) to the UA 202 to open an RTP connection and may send a provisional response to the SA 204 at endpoint A (g) indicating that the SA 204 is “ringing” the user at endpoint B. The SA 204 at endpoint A, in turn, may send provisional STATUS response to the UA 202 to provide a ring indication to the UA 202 at endpoint A (k). The UA 202 at endpoint A may, in some applications, provide the provisional status information to the user application 150 (l) to notify the user that an attempt is being made to ring the user at endpoint B.
The INVITE request at step (h) includes information identifying endpoint A and the media type(s) for the RTP session. The UA 202 notifies the user application 150 that an invitation to a RTP session was received by sending a CALL request (i). The user application 150 replies to the CALL request with an ACCEPT request (j) indicating, in this example, that the user at endpoint B has accepted the invitation to join the RTP session. If the call involves more than one type of media, the user at endpoint B may specify the media to be accepted in the ACCEPT request. For example, if a videoconference is requested, the user at endpoint B may choose to accept the audio and decline the video.
After the user at endpoint B accepts the SIP invitation, the UA 202 sends a MA OPEN request (m) to the MA 206 to open a media connection for an RTP session. The MA 206 at endpoint B opens a UDP connection and sends a MA OPEN response (n) to the UA 202 giving the addresses and port of the media connection for the RTP session. At this point the SIP INVITE request sent at step (e) has not been accepted. The UA 202 at endpoint B sends a SA INVITE response (INVITE 200 OK) to the SA 204 at endpoint B indicating that the SA 204 should accept the invitation to join the RTP session with endpoint A (o). This request includes the media host and port information returned by the MA 206 in the Open response. The SA 204 at endpoint B sends a SIP INVITE response (SIP 200 OK+SDP body) to the SA 204 at endpoint A (p). The SIP INVITE response includes an SDP body confirming the RTP connection parameters required to establish full-duplex communication. The SIP INVITE response is the answer to the SIP INVITE request at step (e). The SA 204 at endpoint A acknowledges the SIP 200 OK response to complete the SIP handshake (q).
At endpoint A, the SA 204 sends an SA INVITE response (r) indicating that the connection requested at step (d) was successfully established. This message includes a call identifier that uniquely identifies the call, and the network address of the host and port at endpoint B used for the media connection. The UA 202 at endpoint A in turn sends a CALL response (s) to the user application 150 indicating that the connection requested at step (a) was successfully established, and sends a PEER request (t) to the MA 206 with the RTP connection parameters contained in the SA INVITE response. At endpoint B, the SA 204 sends an ACK request (u) to the UA 202 responsive to the SIP ACK indicating that the connection with endpoint A was successfully established. The UA 202 in turn sends an ACCEPT response (v) to the user application 150 indicating establishment of a connection with endpoint A. The endpoints A and B can now begin sending and receiving RTP media (w).
To end the session, the user application 150 at endpoint A sends a HANG-UP request to its UA 202 (x). Endpoint B could also end the session in the same manner. The UA 202 at endpoint A sends a SA BYE request to the SA 204 at endpoint B (y) indicating that the RTP session specified in the request should be ended. The SA 204 generates a SIP BYE request (z) based on the SIP session parameters established at step (p) and sends this message to endpoint B. The SA 204 at endpoint B receives the SIP BYE request and replies to acknowledge receipt of the message (aa). At endpoint A, the SA 204 sends a BYE response (bb) to the UA 202 confirming that the RTP session is closed. The UA 202 sends a HANGUP response (cc) to the user application 150 to notify the user application 150 that the RTP session is closed, and sends a CLOSE request (dd) to the MA 206 to close the connection opened for the RTP session. At endpoint B, the SA 204 generates a BYE request and forwards the BYE request to the UA 202 (ee) indicating that the RTP session has been closed. The UA 202 at endpoint B sends a HANGUP request (ff) to the user application 150 to notify the user application that the RTP session is closed, and sends a CLOSE request (gg) to the MA 206 to close the connection opened for the media session (gg).
In some embodiments of the invention, the MA 206 may be capable of routing media directly to media rendering devices, bypassing the user application 150 when the user application 150 does not need to process the data. For example, in media streaming, the user application 150 typically receives the media stream and outputs the media stream to a media player without any data processing. The MA 206 can, in this situation, directly route the media stream to a media player.
In a preferred embodiment of the invention, the user application 150 can direct how media or messages are routed. To enable selective routing of media by the user application 150, the UA API may include a SETROUTE request that is sent by the user application 150 to the media client 200 to specify particular sources or sinks for media streams. The sources or sinks may be internal or external to the mobile terminal 100. The MA API includes a corresponding SETROUTE request that is sent by the UA 202 to the MA 206 to configure routing tables specifying how media streams are to be routed. The UA API and MA API may also include other requests to control the media stream, such as a PAUSE request to pause an active media stream, and a RESUME request to resume a paused media stream.
To initiate a media session, the application 150 in the mobile device 100 uses the procedure shown in
In the example shown in
To remotely control the DVD player 400, the mobile device 100 establishes an MSRP session with the DVD player 400 for transmitting commands and/or control signals to the DVD player, and a separate RTP session for streaming video and/or audio from the DVD player 400 to the mobile device 100. The MSRP and RTP sessions are established using procedures as shown in
The method illustrated in
The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
This application claims priority to Provisional U.S. Patent Application No. 60/640,583 filed Dec. 31, 2004, which is incorporated herein by reference.
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