I have downloaded Zoiper v 3.5.3, and installed this on 4 iOS devices, but in all 4 cases the registering procedure is failing. ("Unauthorized 401"). So not a hardware problem,
I am using Zoiper on my notebook computer (Win7), so I know I have the correct account details and password. VoiP ISP is Exetel Australia. I've checked in a number of forums, and I am sure I'm entering the infomation correctly for the devices.
The devices are iPhone 4S , iPhone 6, and 2x iPad 2.0, all with iOS v8 or later.
I 've also tried with and without Outbound Proxy, and +/- STUN.
and deleted account twice and started again.
Can anyone help me with this problem please?