We are using FreePBX 188.8.131.52 with Twilio as our inbound and outbound SIP trunking provider. Everything is working well EXCEPT for an annoyance that the inbound (to us) caller ID has “+1” at the start and the “redial” function on our phones (Cisco CP-8841-3PCC) seems to balk at redialing numbers that start with “+”.
How do we strip that “+” before it gets to the phone?
If you are in the US, on your Trunk, set the context to “from-pstn-e164-us” . That will normalize the inbound caller ID. If you are outside the NANP area, you can use that context from extensions.conf as a template to fix the CID number in your calling area.
We “solved” our problem a slightly different way. The phone configuration itself has a dial plan. The administrator manual would lead one to believe that “+” is not a valid part of a dial plan, but it can be used and does work.