Select a Cisco WAN media gateway or media gateway controller (MGX-based) as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and locate srcpPeerGrpTimeSinceHeartbeat under the srcpPeerGrpParamEntry branch of CISCO-WAN-SRCP-MIB, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. It reports, in milliseconds, how long it has been since the last SRCP heartbeat was received from the peer media gateway controller. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is an Integer32-type OID, Value bounds is the most useful condition here — trigger an alert if this value exceeds 30,000 (30 seconds), which would indicate the peer has stopped sending heartbeats and may have failed. Click Finish to create the monitor; you can adjust any parameter later.