I’ve lived with the issue up to now by sending anything with no CID to an IVR which times out after a few seconds and hangs up the line. This seems to working normally as far as the users are concerned, but I’d really like to get it sorted properly to put an end to these phantom incoming calls.
I’m wondering if it’s voltage related. On outgoing calls, when connected the line is at 9v. If the other end hangs up first, the polarity reverses but stays at this low voltage. Everything is normal.
However, the problem occurs when I hang up first my end. The polarity reverses, but as the line is now idle it also changes from 9v to 50v. It’s only when we get a polarity change AND an increase in voltage together than this “starting post polarity CID detection” is incorrectly triggered.