Cisco ATA188-I2-A Administration Guide - Page 22

72853 H.323 Overview Chapter 1 Cisco Analog Telephone Adaptor Overview Figure 1-2 Cisco ATA 186 as Endpoint in an H.323 Network Telephone/fax V Ethernet Broadband Cisco ATA 186 Broadband CPE (DSL, cable, fixed wireless) Layer 3 IP infrastructure Voice gateway V PSTN H.323 Gatekeeper Figure 1-3 Cisco ATA 188 as Endpoint in an H.323 Network Telephone/fax V Ethernet Broadband Cisco ATA 188 Broadband CPE (DSL, cable, fixed wireless) Layer 3 IP infrastructure Voice gateway V PSTN H.323 Gatekeeper 72854 H.323 Overview H.323 is the International Telecommunication Union (ITU) standard for transmitting voice, video, and data across an IP network. Like other VoIP protocols, the H.323 standard is designed to address the functions of signaling and session management from within a packet telephony network. Signaling allows call information to be carried across network boundaries. Session management provides the ability to control the attributes of an end-to-end call. The H.323 standard includes support for call signaling and control, multimedia transport and control, and bandwidth control for both point-to-point and point-to-multipoint conferences. The H.323 standard includes the following protocols: • Call signaling using the H.225 protocol • Media control using the H.245 protocol • G.711, G.722, G.723, G.728, and G.729 audio codecs • H.261 and H.263 video codecs • Data sharing using the T.120 protocol • Real-time transport protocol (RTP) and RTP Control Protocol (RTCP) for media transport Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator's Guide for H.323 (version 3.0) 1-2 OL-4804-01