Cisco Systems MC-607 manual MC-618, Simplified VoIP over Cable Network

Configuring Subscriber-End Broadband Access Router Features

Voice over IP Operations

Figure 113 Simplified VoIP over Cable Network

Gateway/PSTN

Service provider backbone

CMTS rack	CMTS rack
equipment	equipment

Gatekeeper or	Policy
calling agents	server
HFC	HFC
cable plant	cable plant
Cisco uBR924	Cisco uBR924

	Calling party	Called party
Residence or SOHO		Residence or SOHO
	subscriber site 1	subscriber site 2

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You can deploy IP telephony as a local-loop bypass service where voice packets are transferred from the CMTS to one of the following, depending on the signalling protocol used:

•A telephony gatekeeper when using H.323; the Cisco uBR924 acts as an H.323 gateway.

•A call agent when using SGCP.

The gatekeeper or call agents manage voice calls; the gateway interconnects the IP network to the Public Switched Telephone Network (PSTN). The gatekeeper must be running Cisco IOS Release 12.1 or later in order to support registration of the full E.164 address for each Cisco uBR924 port.

Voice calls are digitized, encoded, compressed, and packetized in the originating gateway, then decompressed, decoded, and reassembled in the destination gateway. A server maintains subscriber profiles and policy information.

You can place and receive calls without using the local exchange carrier. Two simultaneous voice and fax calls are supported to and from each subscriber site. Multiple telephones and fax devices can be connected to each of the two VoIP telephone lines at a subscriber site, providing the 5 REN limit is adhered to for each telephone line.

Note the following requirements and characteristics of VoIP applications using the Cisco uBR924 cable access router:

•The telephones at each subscriber site must support touch-tone dialing; rotary dialing is not supported.

•Special telephone features such as call waiting, call forwarding, and conferencing are not supported.

•A two-line telephone can be connected to the V1+V2 port on the Cisco uBR924.

Cisco IOS Multiservice Applications Configuration Guide

MC-618