When deploying Cisco Emergency Responder (CER) with the primary and secondary servers separated by a WAN, the requirements for this deployment are as follow.
1) Maximum of 40ms round-trip delay between the CER primary and secondary.
2) Minimum bandwidth of 1.544 Mbps between the CER primary and secondary.
3) Maximum of 40ms round-trip delay between each CER server and it's CUCM CTIManager server.
These requirements apply to CER 8.6(1) and prior versions.
