I posted a previous topic about fast busy using CER. I found a cryptic solution buried on the CCO site. It works, but I am unsure of why it works. Within a CSS are multiple partitions lets say Partition A and Partition B. These paritions are ordered so that Partition A is first and Partition B is second. Phone places a 911 call that is correctly routed to the CER. The output of the CER action is a dial pattern with a match within Partition B. The result is a fast busy. If I move Partition B to the top of the CSS list, the call executes as it should.
I thought that CM would search the CSS from the top partition down until it found a match. In this case, it appears that if it does not find a match in the first partition, the calls fails to fast busy.
I can post more details of the exact CSS, partions, route points, CER handling, etc if needed.