IP phone using Acrobits - Groundwire Softphone one way audio

I have the Acrobits Groundwire softphone running on an IPhone (ATT).

My FreePBX is on a routable IP.

The Groundwire will register with no problems. In FreePBX I see the Extension registered with a Host address of and the Port Status as “unreachable”.

I can make inbound calls from the softphone and the receiving party can hear me but I cannot hear them. The Acrobits software identified that there was a one-way audio issue and by purchasing their $.99 monthly NAT Bridge service the problem would be resolved.

  1. The problem wasn’t resolved. Except the message went away.
  2. How does this ever work to allow calls to be made to this phone when it has an internal IP and is “unreachable”.

I cannot be the only person having these issues.

This is the kind of problems I seem to have with any SIP phone behind a firewall/router.

Any ideas? I am missing some basic concept.

Help. Thanks.