Codecs Page 289 of 910
IP Line Description, Installation and Maintenance
The term “codec” refers to the voice coding and compression algorithm used
by the DSPs on the Voice Gateway Media Card. Different codecs provide
different levels of voice quality and compression properties. The specific
codecs, and the order in which they are used, are configured in the LTPS, and
on the system.
Table 54 shows which codecs are supported on the CS 1000 and Meridian 1
systems.
Note: The MVC 2050 supports only the G.711 codec with 30 ms
payload.
Note: If there are multiple nodes on a system and the same codec is
selected on more than one node, ensure that each node has the same voice
payload size configured for the codec.
Table 54
Supported codecs
Codec Payload size
G.711 a-law, G.711 mu-law, NOVAD 10, 20, and 30 ms
G.729A 10, 20, 30, 40, and 50 ms
G.729AB 10, 20, 30, 40, and 50 ms
G.723.1 130 ms
T. 38 2supported for fax calls on gateway channels
G.711 Clear Channel 2supported for fax calls on gateway channels
Note 1: The G.723.1 codec has bit rates of 5.3 Kbps and 6.3 Kbps. In IP Line 4.5, the G.723.1
codec can only be configured with a 5.3 Kbps bit rate; however, the system accepts both
G.723.1 5.3 Kbps and 6.3 Kbps from the far end.
Note 2: T.38 is the preferred codec type for fax calls over virtual trunks. However, the G.711
Clear Channel codec is used if the far end does not support the T.38 codec.