SIP response codes
SIP 403 Forbidden
Forbidden: the server understood the request and refuses it. Repeating it with credentials will not help.
- Name
- Forbidden
- Class
- 4xx · Client error
- Defined in
- RFC 3261
- Produced from Q.850 causes
- 21, 55, 57, 87
When it happens
- Wrong credentials after too many attempts (fail2ban or carrier lockout).
- The destination is not allowed for this account: international, premium or a blocked prefix.
- Calls from an IP address the trunk does not allow.
- Caller ID not allowed by the carrier.
- No balance on a prepaid account.
What to check
- Check the account’s calling rights and balance with the provider.
- Make sure the source IP is whitelisted on the trunk.
- Check the number format the carrier expects (+E.164 or national) and the caller ID you send.
What the response looks like
SIP/2.0 403 Forbidden
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=21;text="Call rejected"
Content-Length: 0