Page 68 of 378 Description
553-3001-202 Standard 1.00 April 2000
Codec profiles
Codec refers to the voice coding and compression algorithm used by the
DSPs on the ITG ISL Trunk card. The G.XXX series of codecs are standards
defined by the International Telecommunications Union (ITU). Differe nt
codecs have different Quality of Service and compression properties. The
specific codecs and the order in which they are to be used for codec
negotiation is configured in MAT.
When configuring the ITG Node in MAT, select the image containing the
needed codecs, and the preferred codec negotiation orde r. Th e fina l codec
used is determined by the codec negotiation process with the far end durin g
call setup. Parameters can be configured for each codec in an image.
The ITG supports the following codecs:
• G.711
• G.729A
• G.729
• G.723.1

G.711

The G.711 codec delivers “toll quality” audio at 64 kbit/s. This codec is
optimal for speech quality, as it has the smallest delay and is resilient to
channel errors. However, it uses the largest bandwidth. The G.711 codec is
the default codec if the preferred codec of the originati ng node is not available
on the destination ITG ISL Trunk node. Voice Activity Detection/ Silence
Suppression is configurable through MAT. 24 channels per card are
supported with G.711.

G.729A

The G.729A codec is the default preferred codec when adding a new ITG
Trunk node in MAT. This codec provides near toll quality voice at a low
delay. The G.729A codec uses compressi on at 8 kbit/s (8:1 compress ion rate ).
Optional AnnexB Voice Activity Detection/Silence Suppression is
configurable through MAT. 24 channels pe r card are s upporte d wi th G.729 A.