Dialogic 6.2 - Manual (Page 230)

Failover Based on Telephony Cause Codes
November 2009 230
Failover Based on Telephony Cause Codes
Overview
Identifying call failures within an IP telephony network allows an
application to re-route calls depending on the failure. In many cases,
the failover to other network devices occurs seamlessly when the
network has the following:
„ H.323 Gatekeepers
„ SIP Registrar Servers or SIP Redirect Servers
In cases where the network does not have these components, the
failover responsibility falls on the application.
Typically, in the absence of gatekeepers or other call routing devices,
the telephony endpoint, under the control of the application, is in
direct contact with the gateway. In this network configuration, the
application must be able to identify the various types of failures in
order to effectively manage the call routes.
Common Failures
The following are some common failures:
„ Unreachable IP address
„ Reachable IP address with no SIP/H.323 response
„ Gateway SIP/H.323 channels exceeded
„ Gateway PSTN channels exceeded
„ Gateway with responding SIP/H.323 and PSTN down (no PSTN
cable connected)
„ Gateway with responding SIP/H.323 and PSTN down due to an
alarm
„ Gateway with responding SIP/H.323 and PSTN up but not
waiting for calls
„ Gateway failure during an active call by disconnecting the
network cable on SR140
„ Gateway failure during an active call by disconnecting the
network cable on the gateway