I have two Windows phone 8 and 10, With 8 I don't have any Problems. With the Windows 10 Phone I get bad Request 400 error. I can't me Register to Sipgate.
I have found the problem....not here....
400 bad Request / P-Registrar-Error: Contact/received too long
Contact has 3x lines Code with: X-PUSH-URI=http://e.notify.live.net/u/
Result: Enable Push: disable