Dialogic 6.2 Manuale Utente

Failover Based on Telephony Cause Codes

November 2009

230

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.  

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