Common Causes for SIP Outbound Call Failures

1. Caused by diversion header

Set Diversion to None in the setting: Trunk > Advanced > Outbound Parameters, Diversion

2. Incorrect Caller ID number in sip message

Set the trunk number in the Caller ID Number field or PBX will send the original extension out to the provider.

SIP Trunk> Basic>  Caller ID Number

3. The provider doesn’t support video codec

Disable the video codec on trunk: Trunk > Codec

4. The provider doesn’t support re-invite

PBX send sip re-invite attempt to negotiate the endpoints to route RTP to each other directly, bypass the system.

Disable the re-invite on PBX: General> SIP> Advanced, Allow RTP Re-invite

What you can do if those configurations do not help?