When it happens
- A ported or disconnected number.
What to check
- Remove the number from your lists; check whether it has a new number.
What the response looks like
SIP/2.0 410 Gone
Via: SIP/2.0/UDP 203.0.113.10:5060;branch=z9hG4bK776asdhds
From: <sip:101@pbx.example>;tag=1928301774
To: <sip:+15551234567@pbx.example>;tag=a6c85cf
Call-ID: a84b4c76e66710@203.0.113.10
CSeq: 2 INVITE
Reason: Q.850;cause=22;text="Number changed"
Content-Length: 0