Supported Codecs; Streaming Audio Server And Music On Hold - Linksys SPA1001 Administrator User Manual

Feature Descriptions
exists, the DNS server returns an SRV record that contains a list of SIP proxy servers for the domain,
with their host names, priority, listening ports, and so on. The Linksys ATA tries to contact the list of
hosts in the order of their stated priority.
If the Linksys ATA is currently using a lower priority proxy server, it periodically probes the higher
priority proxy to see whether it is back on line, and switches back to the higher priority proxy when
possible.

Supported Codecs

Negotiation of the optimal voice codec sometimes depends on the ability of the Linksys ATA device to
match a codec name with the codec used by the far-end device. The Linksys ATA allows the network
administrator to individually name the various codecs that are supported so that the Linksys ATA can
successfully negotiate the codec with the far-end equipment. The administrator can select which
low-bit-rate codec is to be used for each line. G.711a and G.711u are always enabled.
Table 1-3
Codec (Voice Compression
Algorithm)
G.711 (A-law and mμ-law)
G.726
G.729A
G.723.1
When no static payload value is assigned per RFC 1890, the Linksys ATA can support dynamic payloads
Note
for G.726.

Streaming Audio Server and Music on Hold

This feature allows you to attach an audio source to one of the Linksys ATA FXS ports and use it as a
streaming audio source device. The corresponding Line (1 or 2) can be configured as a streaming audio
server (SAS) such that when the Line is called, the Linksys ATA answers the call automatically and
Linksys ATA Administrator Guide
1-6
Codecs Supported by Linksys ATAs
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. Linksys 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 Linksys ATA 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.
Chapter 1 Introducing Linksys Analog Telephone Adapters
Document Version 3.1