Source note · DNS SRV and service discovery for SIP
Under RFC 3263, when the target is a numeric IP address or the URI carries an explicit port but no transport parameter, the client uses UDP for a sip URI and TCP for a sips URI.
Checked 2026-09-24
- Vendor
- IETF
- Product
- SIP
- Subsystem
- transport selection
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3263 (June 2002)
- Checked
- 2026-09-24
Sources
- RFC 3263: Session Initiation Protocol (SIP): Locating SIP Servers — RFC Editor / IETF · tier 1 standards and regulators · Section 4.1 Selecting a Transport Protocol
Cite this note
APA
WarmTransfer. (2026, September 24). DNS SRV and service discovery for SIP: source note dns-srv-voice-rfc3263-explicit-target-transport. WarmTransfer. https://warmtransfer.net/knowledge/claims/dns-srv-voice-rfc3263-explicit-target-transport
BibTeX
@misc{warmtransfer-claim-dns-srv-voice-rfc3263-explicit-target-transport,
title = {DNS SRV and service discovery for SIP: source note dns-srv-voice-rfc3263-explicit-target-transport},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/dns-srv-voice-rfc3263-explicit-target-transport},
note = {Source note dns-srv-voice-rfc3263-explicit-target-transport, checked 2026-09-24}
}