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Failover Based on Telephony Cause Codes
November 2009 233
Known Failures From Various Gateways
H.323 and SIP
In Table 11, the entries are divided between H.323 and SIP. In the
case of H.323, cause codes are sent by the gateway as values
corresponding to Q.931 error codes. These are returned unaltered by
BfvLineTerminateCall(). In the case of SIP, the gateway sends SIP
error codes which are then translated by BfvLineTerminateCall()
into Q.931 error codes before being returned.
Using cause codes to determine failover scenarios is complicated. In
most cases, the cause codes supplied by the gateway are
manufacturer-specific and depend on the protocol being used.
Applications needing specific information about a call failure can use
the cause codes reported by BfvLineTerminateCall() or
BfvCallWaitForComplete(). Note when the Bfv API function returns
BT_STATUS_TIMEOUT, the cause code will not be valid.
Table 11. Known Failover Cause Code Data
Scenario SR140
Protocol
GnuGK Alcatel Avaya SIP
Control
Cisco
2821
CCM6.01 CCM6.1 Quintum IM1010
H.323
Unreachable IP
Address
H.323 1000 1000 1000 1000 1000 1000 1000 1000 1000
Reachable IP address
with no SIP/H.323
responds
H.323 1000 1000 1000 1000 1000 1000 1000 1000 1000
Gateway failure during
an active call by
disconnecting the
network cable on the
SR140
H.323 0, 16 0, 16 0, 16 0, 16 0, 16 0, 16 0, 16 0, 16 0, 16
Gateway failure during
an active call by
disconnecting the
network cable on the
gateway
H.323 0 0 0 0 0 0 0 0 0