// SIP 6xx Global failure

SIP 603 Decline

The callee does not want to take the call, here or anywhere.

6xx Global failure · RFC 3261 · Answer to OPTIONS: Answering. It declined us.

What SIP 603 means

A 603 says the callee's device was reached, but the user, or the system acting for them, doesn't want to take the call. It is a global failure: the decline covers every location of that user, so a proxy shouldn't try other devices. The response may carry Retry-After to suggest a better time to call.

You usually see 603 on INVITE when someone presses reject on a phone, or when call screening, an anonymous-call filter or a do-not-disturb setting refuses the call. A gateway that passes a 603 on to the phone network maps it to Q.850 cause 21, call rejected, under RFC 3398.

Example response

SIP/2.0 603 Decline
Via: SIP/2.0/UDP 198.51.100.33:5060;branch=z9hG4bK-603-a6
From: "Anonymous" <sip:[email protected]>;tag=5c3e
To: <sip:+[email protected]>;tag=dc-4b
Call-ID: [email protected]
CSeq: 1 INVITE
Retry-After: 3600
Content-Length: 0

Common causes of SIP 603

The user pressed reject, or the phone is set to decline calls instead of sending them to voicemail.
A call-screening rule refused the caller, for example one that blocks anonymous or withheld numbers.
Do-not-disturb is configured to answer with a decline rather than with 480 or 486.
The called system blocks calls from your caller ID or trunk, for example as suspected spam.

How to fix SIP 603

Check whether a person declined the call or a rule did; a decline in under a second is usually a rule.
Try the call with a different, non-anonymous caller ID to see whether screening is the cause.
Ask the owner of the called number to check their blocking, screening and do-not-disturb settings.
If your calls are being declined as unwanted, check that your caller ID is valid and presented correctly.

SIP 603 as an answer to OPTIONS

A 603 to OPTIONS means the server is answering, but it declined the probe. That is a deliberate refusal rather than a fault, often a policy against unknown senders. A PingVo Route counts it as reachable by default; set the Route's expected codes to 200 if a decline should count as a failure.

See which code your SBC returns. Run a free SIP OPTIONS check

Questions about SIP 603

What is the difference between SIP 603 and 486?

486 says the callee is busy at this device and might be free elsewhere. 603 says the callee won't take the call anywhere.

What is the difference between SIP 603 and 607?

603 is a plain refusal. 607 Unwanted says the callee marked the call as unwanted, such as spam, which lets the network learn from it.