Source note · SIP response codes and failure interpretation
A 603 Decline means the destination machine was contacted successfully and the user explicitly does not wish to or cannot participate and is returned only when the client knows no other endpoint will answer.
Checked 2026-09-15
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- response codes
- Deployment
- not restricted
- Region
- not restricted
- Release range
- current as of 2026-09-15
- Checked
- 2026-09-15
Sources
- RFC 3261 — SIP: Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · RFC 3261 section 21, 603 Decline
Cite this note
APA
WarmTransfer. (2026, September 15). SIP response codes and failure interpretation: source note sip-603-decline. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-603-decline
BibTeX
@misc{warmtransfer-claim-sip-603-decline,
title = {SIP response codes and failure interpretation: source note sip-603-decline},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-603-decline},
note = {Source note sip-603-decline, checked 2026-09-15}
}