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The Out-of-dialog (OOD) Options Ping feature provides a keepalive mechanism at the SIP level between any number of destinations. A generic heartbeat mechanism allows Cisco Unified Border Element to monitor the status of SIP servers or endpoints and provide the option of busying-out a dial-peer upon total heartbeat failure. When a monitored endpoint heartbeat fails, the dial-peer is busied out. If an alternate dial-peer is configured for the same destination pattern, the call is failed over to the next preferred dial peer, or else the on call is rejected with an error cause code.

The table below describes error codes option ping responses considered unsuccessful and the dial-peer is busied out for following scenarios:

All other error codes, including 400 are considered a valid response and the dial peer is not busied out.

Note	The purpose of this feature is to determine if the SIP session protocol on the endpoint is UP and available to handle calls. It may not handle OPTIONS message but as long as the SIP protocol is available, it should be able to handle calls.

When a dial-peer is busied out, Cisco Unified Border Element continues the heartbeat mechanism and the dial-peer is set to active upon receipt of a response.

1.    enable

2.    configure terminal

3.    dial-peer voice tag voip

4.    voice-class sip options-keepalive {up-interval seconds | down-interval seconds | retry retries}

5.    exit

The following commands can help troubleshoot the OOD Options Ping feature:

• debug ccsip all --shows all Session Initiation Protocol (SIP)-related debugging.
• show dial-peer voice x --shows configuration of keepalive information.

Router# show dial-peer voice | in options
voice class sip options-keepalive up-interval 60 down-interval 30 retry 5
voice class sip options-keepalive dial-peer action  = active

• show dial-peer voice summary --shows Active or Busyout dial-peer status.

Router# show dial-peer voice summary
           AD                   PRE PASS
TAG TYPE  MIN  OPER PREFIX    DEST-PATTERN KEEPALIVE
111 voip  up     up               0 syst   active 
9  voip   up    down              0 syst   busy-out