Media5-fone and Free-PBX SIP/2.0 403 Forbidden

Has anyone had any experience with the Media5-fone with Free-PBX. I cannot for the life of me get it to register and extension with the app. It keeps saying wrong user and or password. But from where I’m looking it’s all good. If I attach a hard-phone to the extension it all works. I must be missing something daft, if I use the SIP Traces program on the app I get this message SIP/2.0 403 Forbidden.

Any advice would be most appreciated

I had it installed and working perfectly. Got a new Nexus 9 for Christmas and am now having the same problem. Wish I’d written down the settings before my old tablet got wiped.