Session Initialization Protocol (SIP) signaling groups are similar in concept to ISDN PRI signaling groups. No physical hardware components make up the SIP B-channel or SIP D-channel objects discussed here, and no maintenance tests are run.

The SIP signaling group can be considered to be one D-channel that physically rides on a PROCR port and the IP network. Unlike ISDN D-channels, the SIP D-channel may come up and down on a call-by-call basis. The SIP D-Channel is actually a TCP/IP signaling channel. Layers 1 and 2 of this signaling channel can be monitored by IP PING testing.

SIP B-channels use Media Processor ports to carry the actual bearer. Any port of a media processor may serve an H.323 station or a SIP B-channel. Status information may exist for a specific SIP B-channel. A SIP B-channel may be busied out and released.

Errors are logged for command busyout conditions. Under normal conditions, the system automatically places SIP B-channels into or out of service when it receives a SIP signaling-group service state update. A demand busyout drops active calls.