I am working with OCS 2007 R2 in a consolidated FE EE topology, with an Edge server in the DMZ. At first we noticed that there was a problem with conferencing during a live meeting service - the microphone was ghosted. We checked in the FE server, and the A/V conferencing service is not started. Upon starting it, it marked the usual message about some services not starting if they have no work to do. In the Event Viewer, we saw: Source: OCS MCU Infrastructure Event ID: 61031 Failed to start service for the following reasons Failed to initialize TCP/TLS listener for SIP. We have made sure each service on the FE has its own port, and even added another IP address to the NIC specifically for the A/V Service.
We ran the Validation task on the FE server, and identified that the A/V service was using the same port as another service - I believe it was because we didn´t re-start all the services after a previous change of IP/port. Anyway, we sorted out the conflict by assigning another IP address to the server and taking away the "All" option in the IP address for each service.