Features Page 249 of 910
IP Line Description, Installation and Maintenance

Codecs

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 on the LTPS and CS 1000 and
Meridian 1.
Table 49 shows which codecs are supported on the systems.
For detailed information about codecs, refer to “Codecs” on page 287.

Set type checking and blocking

If the registration is a regular request (not a Virtual Office login), the Call
Server checks the configured TN type against the actual IP Phone type. If the
set types do not match, the registration is blocked.
Table 49
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 6.4 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.