Cisco Systems 3600 Configure Codec and VAD for Dial Peers, Configure Codec for a VoIP Dial Peer

Optimize Dial Peer and Network Interface Configurations

To generate an SNMP trap message if the reserved QoS is less than the configured value for a selected VoIP peer, use the following commands, beginning in global configuration mode:

Note RSVP reservations are only one-way. If you configure RSVP, the VoIP dial peers on both ends of the connection must be configured for RSVP.

Configure CODEC and VAD for Dial Peers

Coder-decoder (CODEC) and voice activity detection (VAD) for a dial peer determine how much bandwidth the voice session uses. CODEC typically is used to transform analog signals into a digital bit stream and digital signals back into analog signals—in this case, it specifies the voice coder rate of speech for a dial peer. VAD is used to disable the transmission of silence packets.

Configure CODEC for a VoIP Dial Peer

To specify a voice coder rate for a selected VoIP peer, use the following commands beginning in global configuration mode:

The default for the codec command is g729r8; normally the default configuration for this command is the most desirable. If, however, you are operating on a high bandwidth network and voice quality is of the highest importance, you should configure the codec command for g711alaw or ulaw. Using this value will result in better voice quality, but it will also require higher bandwidth requirements for voice.

For example, to specify a CODEC rate of G.711a-law for VoIP dial peer 108, enter the following:

dial-peer voice 108 voip destination-pattern +14085551234 codec g711alaw

session target ipv4:10.0.0.8

VC-34Voice, Video, and Home Applications Configuration Guide