Bria Teams Config

Using Bria Mobile iOS with FreePBX and one of the requirements for receiving incoming calls is for FreePBX to register with Bria’s push servers:

“The SIP server must allow registration from the Bria Push Server. If the SIP server is running inside a restricted network of an organization, the organization must provide access to the Bria Push Server and set the “SIP Proxy” parameter.”

Can anyone advise how I would go about achieving this? Thanks!