Sip Proxy Redundancy - Cisco SPA2102 Administration Manual

Introducing Cisco Small Business Analog Telephone Adapters
ATA Software Features
NOTE
Cisco Small Business ATA Administration Guide
Codec (Voice Compression
Algorithm)
G.711 (A-law and m -law)
G.726
G.729a
G.723. 1
When no static payload value is assigned per RFC 1890, the ATA device can
support dynamic payloads for G.726.

SIP Proxy Redundancy

In typical commercial IP Telephony deployments, all calls are established through
a SIP proxy server. An average SIP proxy server may handle thousands of
subscribers. It is important that a backup server be available so that an active
server can be temporarily switched out for maintenance. The ATA device supports
the use of backup SIP proxy servers (via DNS SRV) so that service disruption
should be nearly eliminated.
Description
This very low complexity codec supports
uncompressed 64 kbps digitized voice transmission at
one through ten 5 ms voice frames per packet. This
codec provides the highest voice quality and uses the
most bandwidth of any of the available codecs.
This low complexity codec supports compressed 16,
24, 32, and 40 kbps digitized voice transmission at one
through ten 10 ms voice frames per packet. This codec
provides high voice quality.
The ITU G.729 voice coding algorithm is used to
compress digitized speech. Cisco supports G.729.
G.729a is a reduced complexity version of G.729. It
requires about half the processing power to code
G.729. The G.729 and G.729a bit streams are
compatible and interoperable, but not identical.
The ATA device supports the use of ITU G.723. 1 audio
codec at 6.4 kbps. Up to two channels of G.723. 1 can be
used simultaneously. For example, Line 1 and Line 2 can
be using G.723. 1 simultaneously, or Line 1 or Line 2 can
initiate a three-way conference with both call legs using
G.723. 1 .
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