 compliant cable models and cable modem termination systems (CMTSs). The DOCSIS 1.0 standard was never meant to address QoS and hence is deemed fit mostly for Internet style services such as e-mail and Web browsing, and not telephony services. DOCSIS 1.1 was defined to overcome QoS limitations of DOCSIS 1.0. DOCSIS 1.1 allows delineation of traffic flows based on QoS requirements of the service and hence creates an environment where voice and data can be simultaneously carried over the HFC network with varying levels of support. In addition to DOCSIS 1.1, CableLabs also defined interface specifications called PacketCable that can be used to develop interoperable equipment and systems for providing packet-based voice, video and other high-speed multimedia services over the HFC system. The initial focus of the PacketCable specifications is on packet voice services. It specifies elements such as Cable Modem (CM), Multimedia Terminal Adapter (MTA), Cable Modem Termination system (CMTS), Call Management Server (CMS), Announcement Server (ANS), Signaling Gateway (SG), Media Gateway (MG) and Media Gateway Controller (MGC). Note that some of these are The Ultimate Guide to Building and Delivering OSS/BSS same components that will be used by wireline carriers in deploying softswitch based next-generation networks. Also included in PacketCable are protocols for media stream encoding and transport, call signaling, device provisioning, security and privacy, OSS and QoS. The CMTS is a key component of the cable network infrastructure. It often serves as an edge router or IP service switch, feeding into larger switches and routers and supporting DiffServ and MPLS. CMTS can use a variety of standard interfaces to connect to the backbone such as 100-base T Ethernet, gigabit Ethernet, OC-3, OC-12, OC-48 packet over SONET, and even GR-303. Announcement Server Call Management Server HFC Access Network Multimedia Cable (DOCSIS) Terminal Modem Adapter Signaling Gateway Network Media Gateway Controller Multimedia Media Cable HFC Acces