l media gateways that details VoIP signaling. (RTP, RTCP, and MGCP are discussed in Chapter 9.) Finally, Common Open Policy Ser- vices (COPS) is used for controlling access. (COPS is discussed in Chapter 10.) PacketCable is known internationally as IP Cablecom. PacketCable documents have been approved by the Society of Cable Telecommunications Engineers (www. scte.org), which ANSI recognizes as a standard-setting body for cable in North America, and have been approved by the ITU for adoption as worldwide standards. The cable industry is pursuing global standardization, with the objective of achiev- ing worldwide interoperability of services and equipment, vendor independence, ease of interconnection with other operators, and reduced cost through scale of economies. The ITU has approved a suite of CableLabs PacketCable specifications as standards for the international version of services, including VoIP. As discussed in the following sections, three versions of the PacketCable stan- dard are defined today: 1.0, 1.5, and 2.0. PacketCable 1.0 The first service defined for the PacketCable platform is VoIP. The CableLabs PacketCable 1.0 specification deals with transmitting multifeatured IP phone calls over HFC, and it allows four independent IP voice channels through a single cable modem. PacketCable 1.0 consists of 11 specifications and 6 technical Cable TV Networks reports that define the call signaling, QoS, codec, client provisioning, billing event message collection, PSTN interconnection, and security interfaces necessary to implement a single-zone PacketCable solution for residential IP voice services. The core set of PacketCable 1.0 specifications essentially describes how to move the basic functions generally found on traditional Class 5 local exchanges onto a distributed architecture consisting of several general-purpose servers, leading to a low-cost, highly flexible, and scalable solution. PacketCable multimedia defines a generic architecture where application managers request QoS on behalf of a client and