Cisco Systems UBR900 specifications Voice Over IP Operations Simplified VoIP Over Cable Network

Voice Over IP Operations

Figure 4 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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Your company can then deploy IP telephony as a local-loop bypass service where voice packets are transferred from the CMTS to:

•

•

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).

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.

•Fax devices—standard Group III and computer-based Group III machines up to 14,400 baud—are supported in Cisco IOS images that support VoIP.

Configuring the Cisco uBR900 Series Cable Access Routers 11