Route call to IAX and cell until one picks up doesn't work

Asterisk Asterisk Support
1

I have just tried for 2 hours to have a caller ring both an IAX phone (or SIP phone) and an external phone (my cell phone) SIMULTANEOUSLY until the first phone picks up.

I have tried it as

  1. ring group to IAX and external number
  2. ring group to IAX and local extension that is fowarded to external number
  3. call queue to IAX and external number
  4. call queue to IAX and local extension that is forwarded to external number
  5. local extension with Dial to IAX and ZAP number
  6. local extension with Dial to IAX and local extension that is forwarded to external number

In ALL of these cases, the IAX (or SIP) extension rings once then immediately stops ringing once the cell phone starts ringing. Picking up the IAX or SIP phone after it stops ringing yields a dialtone and the cell continues to ring.

I’m willing to try and debug this if someone has some suggestions…