What it means
The call was actively declined. The far end could have taken the call but chose not to. Often intentional, but carriers also use it to reject calls, sometimes for spam or blocking.
SIP/2.0 603 Decline
Common causes
- The user pressed decline
- Do not disturb rejected the call
- The caller is on a block list
- A carrier declined the call, sometimes due to a spam label or reputation
- A policy rejection at the far end
How to fix it
- If intentional, no action is needed
- If unexpected, check block lists and do not disturb at the destination
- For carrier declines, check your number reputation and STIR/SHAKEN attestation, since spam labeling can cause silent rejections
- Contact the carrier if legitimate calls are being declined
See it in your own trace
Paste a full SIP or Asterisk log into the decoder and ladder tools to see exactly where this response appears in the call and what led to it. Everything runs in your browser, so your logs never leave your device.
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