RFC 3263 transport selection uses an explicit transport parameter if present, otherwise a NAPTR lookup, then SRV lookups for supported transports if no NAPTR records exist, and finally defaults to UDP for sip or TCP for sips URIs.

Checked 2026-09-25

Vendor
IETF
Product
SIP
Subsystem
server location
Deployment
any
Region
not restricted
Release range
RFC 3263 (June 2002), current as of 2026-09-25
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). SIP trunk redundancy and failover design: source note sip-trunk-redundancy-design-rfc3263-transport-order. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-trunk-redundancy-design-rfc3263-transport-order

BibTeX

@misc{warmtransfer-claim-sip-trunk-redundancy-design-rfc3263-transport-order,
  title  = {SIP trunk redundancy and failover design: source note sip-trunk-redundancy-design-rfc3263-transport-order},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-trunk-redundancy-design-rfc3263-transport-order},
  note   = {Source note sip-trunk-redundancy-design-rfc3263-transport-order, checked 2026-09-25}
}

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