I am working on CER on VM as test environment until get MCS server from Cisco. It was working fine, but when I restarted "CER" service on CER server, it has been broken. I've restarted the host server, Callmanager service, ... but still busy tone. CTI RPs are registered though. But when I dial 911 from any phone, I got busy tone, and in CER call history I've not seen calls even hit the CER.
Any suggestion regarding how to troubleshoot this issue, would be greatly appreciated.