1/2 Ring Disconnect for return call from cell phone

Unsure where to begin tracing this down. Have a FreePBX instance running and using a SIP trunk and DID from Twilio as a provider for inbound and outbound trunks. All works except 1 thing…

If I initiate an outbound call from FreePBX using the Twilio trunk, and I call my cellphone the caller ID on my cellphone shows up as +1 XXX-XXX-XXXX

If I then go to my call history on my phone and try to call the number back, it rings once or a half ring and then disconnects the call immediately. If I remove the +1 and just dial XXX-XXX-XXXX the call completes as expected. It gets routed to FreePBX and the call is connected.

I am not sure if the reason I cannot get +1 XXX-XXX-XXXX to work from my cell is related to my cell phone, the Twilio trunk, a setting within FreePBX or what. Also not sure what log I could look at within FreePBX to determine if the attempt to +1 XXX-XXX-XXXX is even being reached.

I’m not a Twilio customer, but here are some general suggestions for tracking this down.

On the +1 calls from your mobile, what (if anything) appears in the Asterisk log? If something is logged, turn on pjsip logger and compare a +1 call and a 10-digit call. You may just need a second Inbound Route to accommodate a different DID format, or you could use the from-pstn-e164-us context to normalize the numbers.

If nothing logged, what (if anything) is logged in your Twilio account?

If nothing there, either, can you successfully call other (non-Twilio) numbers from your mobile using the +1 format?

In what format do calls from other sources appear on your mobile?

How do calls via Twilio appear on a mobile using a different carrier? What happens on calls to your PBX from that mobile?