Issues that I have experienced are associated with a lot errors on the E1.0 PCM system. The circuits would go into the Temporary_Out_Of_Service or Out_Of_Service state. Circuits would have to be Blocked and “restarted”. In the past we would manually block circuits that had a high level of CRC errors. These circuits would then be analysed to see if the issue was Hardware (e.g. ET), Hardware, MML configuration, Software issues with the SS7 software module, etc..
VBR/ Wallis Dudhnath