Have multiple phones using Zoiper with Verizon and TMobile for our business (technicians in the field, want the main phone line to ring everyone). Got a new employee who uses AT&T and cannot get Zoiper to register when he is on AT&T network. Works fine in his home when on WiFi or in our store on WiFi, but not with network. Not seeing a lot in online searches.
Checked his credentials by using them on another network phone (Verizon), and it registered just fine.
Using IPytomy PBX.
Anyone know of any settings with AT&T that may prevent Zoiper from registering?