VoIP calls using Sofphone app on Android

[#1]

I use the Acrobits Softphone app to make and receive VoIP calls on my Android mobile. My VoIP service is provided by A&A.

The app registers and works when the phone is conected to WiFi, but it says 'unauthorized' when connected to the mobile network.

Acrobits say that the app should work when the phone is connected to the mobile network, but mine doesn't.

There is probably some setting that I need to change, but I am out of my depth. Any ideas?

[#2]

@Jones 

Acrobits say that the app should work when the phone is connected to the mobile network

That's a very brave statement by them!.

ISTR that in the past , some mobile networks blocked SIP traffic. I don't know if that's still the case ?

Even if it isn't, then there's the question of CGNAT. Many mobile networks use CGNAT and this can cause problems with SIP.

[#3]

@MisterW 

Thank you. 

Acrobits mention possible problems with 3G networks, so I assumed . . .

I'll give up trying now. 

[#4]

If you have a VPN or such like running you may have more success over that.

[#5]

Thank you @dvorak 

I achieved my main objective, which was to be able to receive calls on my mobile and stream the callers voice to my hearing aids. Making and taking calls while I am out and about was a secondary consideration.