The trick is to use the call trace function to find if calls already exist in the system.
There is a limit on the number of stored calls in memory of the call trace function.
See: https://docs.telcobridges.com/mediawiki/index.php/Call_Trace
Rouitng Script attached, instructions in the file.
Attachments
reject_if_call_exist_filter.zip (2 Kb) Downloaded 14 times