Hi, i'm using 3cx with inphoniesx VOIP and they wouldn't know the answer to this question so perhaps people on this forum have more knowledge of this situation. Softphone and granstream are working fine connected directly to voip but dont work through 3cx no matter what i try. on a start up logs give me this 07:25:50.033 [CM504005]: Registration failed for: 10000@InPhonex - Worldwide; Cause: 403 Call cannot be served here; from IP:188.8.131.52:5060 btw. what is extension 10000? Any ideas please?