Configuring resiliency into UC Voice gateway connecting to a CUCM Cluster via SIP Trunks. Typically we would configure retry timers and counts to force the IOS Gateway to route via lower preference dial-peers. With the introduction of SIP Options, we can now effectively shut the dial-peer down (busy-out) if the IOS Gateway cannot reach the CUCM Server within the configured thresholds. This is a proactive method to ensure calls are not being delayed toward the CUCM Cluster. Change the SIP Options Keepalive Up/Down timers to suit your requirements.

I’ve listed below the general Voice Class and relevant dial-peer configuration.

Voice Class

voice class sip-options-keepalive 1
 down-interval 40
 up-interval 20

Dial Peer

dial-peer voice 10 voip
 preference 1
 destination-pattern 0212348[12]..
 session protocol sipv2
 session target ipv4:192.168.41.20
 incoming called-number .
 voice-class codec 1
 voice-class sip options-keepalive profile 1
 dtmf-relay rtp-nte
 no vad

dial-peer voice 11 voip
 preference 2
 destination-pattern 0212348[12]..
 session protocol sipv2
 session target ipv4:192.168.51.20
 incoming called-number .
 voice-class codec 1
 voice-class sip options-keepalive profile 1
 dtmf-relay rtp-nte
 no vad

Verify

To verify both dial-peers are operational run the below cmd.

show dial-peer voice summary