Abstract:
A multimedia terminal adapter for a “data over cable” system includes a host processor. A network interface may be coupled to a cable modem termination system via a cable transceiver. The adapter includes a plurality of device ports. An applications platform is executed on the host processor for providing standardized application program interfaces for allowing compliant application programs to access network services via the network interface to provide multimedia content to at least one of the device ports. A SIP proxy is provided for responding to interconnection of a SIP-compatible device to one of the device ports and for intermediating access to SIP-based services via the network interface.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   Not Applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   The present invention relates in general to providing multimedia services from a data network such as the Internet to users of cable systems, and, more specifically, to increasing the users&#39; access to voice and video multimedia services with improved network performance. 
   PacketCable standards have been developed to provide a cable system/IP network architecture to deliver point-to-point multimedia services, such as voice over IP (VoIP). The architecture includes a multimedia terminal adapter (MTA) which may be integrated with a cable modem or connected to a separate cable modem. The MTA performs signal manipulations (e.g., encoding/decoding and A/D and D/A conversion) and implements various network protocols. 
   The various network services that may be provided to the cable customer typically require corresponding applications to be installed in the MTA. A standard software environment known as the OpenCable applications platform (OCAP) has been developed to encourage compatibility and reduce hardware/software costs. OCAP includes a set of application programming interfaces (API&#39;s) that provide an operating system (i.e., middleware) for the application programs themselves. The API&#39;s comprise Java software packages that provide program access to basic system resources. An OCAP compliant application program can thus run on any OCAP compatible devices to access network services and multimedia content, among other functions. 
   The types of services contemplated to be implemented using OCAP include various interactive services such as electronic program guides, voice over IP (VoIP), video telephony, video on demand (VOD), and other services. However, the OCAP model does not enable other types of client/server applications. 
   One known means of establishing point-to-point communication sessions via the Internet is by using the session initiation protocol (SIP). The SIP protocol performs various functions including determining location of a target endpoint, determining media format capabilities of the session endpoints (using the session description protocol, “SDP”), determining availability of a target endpoint, establishing an active session between endpoints, and terminating an active session. MTA&#39;s have become available which support the SIP protocol and which allow access to telephony services by acting as a SIP client. However, these methods provide limited access to SIP-based services by requiring that any particular service be preprogrammed in the MTA and they cannot provide adequate control over communication parameters, such as QoS parameters. 
   SUMMARY OF THE INVENTION 
   The present invention has the advantage of extending access within a cable modem environment to SIP-based services from SIP-based and non-SIP-based devices in a manner which enables prioritization of selected SIP-based services over other network services. 
   In one aspect of the invention, apparatus is provided including a host processor. A network interface may be coupled to a cable modem termination system via a cable transceiver. The apparatus includes a plurality of device ports. An applications platform is executed on the host processor for providing standardized application program interfaces for allowing compliant application programs to access network services via the network interface to provide multimedia content to at least one of the device ports. A SIP proxy is provided for responding to interconnection of a SIP-compatible device to one of the device ports and for intermediating access to SIP-based services via the network interface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of a cable/IP network according to the present invention. 
       FIG. 2  is a block diagram showing the multimedia terminal adapter of  FIG. 1  in greater detail. 
       FIG. 3  is a flowchart showing a preferred method of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The OpenCable applications platform set of API&#39;s that is being developed by the cable industry standardizes a common operating system for all set top boxes and multimedia terminal adapters so that there is an economy of scale which reduces manufacturing costs and eases deployment of various cabled delivered services. The architecture to date has not allowed or accommodated delivery of SIP-based services to end-users connected to the set top box or MTA. The present invention provides a SIP proxy capability within the set top box or MTA along with the OCAP platform. The set top boxes or MTA&#39;s intelligently select one of the functionalities in response to services requests presented to the set top box or MTA. 
   An overall architecture of the present invention is shown in  FIG. 1 . A headend cable modem termination system (CMTS)  10  is connected to a cable distribution network  11  which may comprise a combination of optical fiber and coaxial cable to distribute cable system signals over distribution lines  12  to customer sites including a site  13 . CMTS  10  may be connected a conventional cable television signal source (not shown) and to an Internet service provider network  14  providing an interconnection with Internet  15 . In order to provide telephony services to remote sites, ISP  14  is also coupled with a gateway  16  to the public switched telephone network (PSTN)  17 . 
   The distribution line  12  into customer site  13  is coupled to a set top box  20  or alternatively directly to a television having a cable tuner. To provide data-over-cable services, a cable modem  21  has a transceiver  22  connected to the distribution line. A conventional residential gateway  23  may be coupled to cable modem  21  to provide network access for a personal computer  24 . 
   In order to provide network access for a variety of services to a variety of different end user devices (e.g., non-general purpose computing devices), a multimedia terminal adapter (MTA)  25  is coupled to cable modem  21 . MTA  25  has device ports  26 ,  27  and  28  coupled respectively to a dedicated phone instrument  30 , a SIP network device  31 , and a non-SIP network device  32 . 
   MTA  25  provides an integrated environment for a diverse range of network services including voice services to phone  30 . Phone  30  may comprise an analog telephone instrument for interfacing with the SIP proxy in MTA  25 . SIP network device  31  may comprise a SIP-based phone for likewise accessing voice services. Alternatively, SIP network device  31  may also access video data and other media types as known in the art. SIP-based services may include voice over IP (VoIP), video conferencing, voice conferencing, messaging (e.g., instant messaging, and point-to-point), and multimedia delivery (e.g., prerecorded movies, videos, and music). 
   Non-SIP network device  32  utilizes OCAP API&#39;s within MTA  25  to access other multimedia and network services. 
   MTA  25  is shown in greater detail in  FIG. 2 . MTA  25  may be integrated with a cable modem  21  as shown, to form an embedded MTA (eMTA)  35 . 
   MTA  25  includes a host processor  36  which operates in accordance with published standards (including PacketCable, OpenCable, and DOCSIS specifications, for example). A network interface  37  couples host processor  36  to cable modem  21 . Host processor  36  is coupled to a plurality of device ports  38 ,  40 ,  41  and  42 . Device port  38  includes an RJ11 connector (i.e., a conventional telephone jack) for connecting to a standard analog phone instrument  43 . Thus, port  38  comprises a SIP-only port that receives only SIP-based services. Consequently, any activity from an external device connected to device port  38  can be detected as a request for a SIP-based service. 
   Device ports  40 - 42  preferably include an RJ45 Ethernet connector. A network device  44  is coupled by appropriate cabling to device port  41 . Network device  44  may be a SIP-capable device or a non-SIP-capable device which generates request messages that are coupled to host processor  36  via port  41 , wherein a request message identifies whether the requested service is a SIP-based service. 
   MTA  25  includes application platform API&#39;s  45  coupled to host processor  36  for handling requests for OCAP-based services. A SIP proxy  46  is coupled to host processor  36  for handling requests for SIP-based services. SIP proxy  46  acts as both a server and client to deliver SIP-based services to a SIP client device such as phone instrument  43  or network device  44 . Thus, SIP proxy  46  is an intermediary between a remote SIP-based service provider and the SIP client device. SIP proxy  46  further interacts with host processor  36  to provide additional controls over SIP-based network sessions (e.g., QoS parameters). SIP proxy  46  is preferably comprised of a software module implemented within host processor  36  and/or executed on host  36 . 
   A logic block  47  classifies network service requests as being either a SIP-base request or an applications platform request. Block  47  is a software element executed by host processor  36 . A table  48  may be coupled to logic block  46  to help identify or classify different service requests. 
   A quality of service (QoS) module  50  is coupled to host processor  36  for handling QoS management of network sessions. In handling SIP-based service requests, SIP proxy  46  has access to QoS management via QoS module  50  to ensure that high priority (e.g., voice) applications are handled with reduced network latency as compared to other service sessions. 
   A preferred method of the invention is shown in  FIG. 3 . In step  51 , the host processor monitors the device ports to detect network service requests from user devices connected to the ports. In step  52 , a user initiates a service request via the user device. For example, in the case of an analog phone connected to a SIP-only device port, the user taking the phone off hook is detected by the host processor and is interpreted as a SIP-based service request for completing a voice call to a remote telephone. In the case of a digital network user device connected to an Ethernet port, a service request is initiated by transmitting a request message formed as a network packet transmission from the user device to the host processor. 
   A service request is classified in step  53  as a SIP-based service request or an applications platform service request. The classification is made by the logic block in accordance with predetermined aspects of the request such as an off-hook activity on a SIP-only port or the particular contents of a request message received from a digital network type device. Classification may include comparison of particular information contained in a request message with predetermined data stored in the table coupled to the logic block in order to determine whether the network service being requested is SIP-based or not. 
   A check is made in step  54  to determine whether the service request is for a SIP-based service. If not, then the applications platform is invoked in step  55  to service the request. 
   If a SIP-based service request is detected in step  54 , then the SIP proxy is invoked in step  56  to service the network service request by establishing a SIP network session. In step  57  of the preferred embodiment, the SIP proxy and/or host processor identify a SIP-based service type wherein the type corresponds to a differentiation in QoS levels needed to successfully implement various SIP-based services. For example, a real time voice call (e.g., using VoIP) is typically given higher network priority than other forms of messaging or file downloading, for example. Handling of the particular SIP-based service request is prioritized in step  58 . In particular, transmission of network packets associated with the network service request may be prioritized in response to the SIP-based service type. Prioritization preferably comprises the assignment of a QoS level (e.g., a Class of Service designator) to the transmitted data packets of a particular network session. 
   The SIP proxy interfaces with the QoS module and host processor in order to provide selectable and/or predetermined QoS service levels as desired. In addition, the SIP proxy provides both a user-agent client and a user-agent server as peers for intermediating between endpoints of a SIP session. The SIP proxy interacts with redirect servers, registrar servers, and location servers via the network interface in a known manner.