Source note · Calls-per-second limits on SIP trunks and dialers
RFC 3261 says a client receiving 503 Service Unavailable should try an alternate server and should not send further requests to that server for the Retry-After period if one is given.
Checked 2026-10-02
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- SIP response codes
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3261
- Checked
- 2026-10-02
Sources
- RFC 3261 — SIP: Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · Section 21.5.4
Cite this note
APA
WarmTransfer. (2026, October 2). Calls-per-second limits on SIP trunks and dialers: source note sip-trunk-cps-limits-rfc3261-503-alternate. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-trunk-cps-limits-rfc3261-503-alternate
BibTeX
@misc{warmtransfer-claim-sip-trunk-cps-limits-rfc3261-503-alternate,
title = {Calls-per-second limits on SIP trunks and dialers: source note sip-trunk-cps-limits-rfc3261-503-alternate},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-trunk-cps-limits-rfc3261-503-alternate},
note = {Source note sip-trunk-cps-limits-rfc3261-503-alternate, checked 2026-10-02}
}