Source note · Passing call context with SIP UUI and custom headers
Because RFC 7433 hex encoding uses two characters per octet, a 128-octet isdn-uui payload plus protocol discriminator takes about 258 hex characters on the wire, so vendor '128 character' limits and RFC '128 octet' limits are not the same budget.
inferred · Checked 2026-10-02
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- SIP User-to-User header
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 7433 and RFC 7434
- Status
- inferred
- Checked
- 2026-10-02
Sources
- RFC 7434: Interworking ISDN Call Control User Information with SIP — IETF / RFC Editor · tier 1 standards and regulators · Sections 3.1 and 9 combined with RFC 7433 Section 4 (encoding=hex)
Cite this note
APA
WarmTransfer. (2026, October 2). Passing call context with SIP UUI and custom headers: source note sip-uui-context-passing-hex-doubles-wire-length. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-uui-context-passing-hex-doubles-wire-length
BibTeX
@misc{warmtransfer-claim-sip-uui-context-passing-hex-doubles-wire-length,
title = {Passing call context with SIP UUI and custom headers: source note sip-uui-context-passing-hex-doubles-wire-length},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-uui-context-passing-hex-doubles-wire-length},
note = {Source note sip-uui-context-passing-hex-doubles-wire-length, checked 2026-10-02}
}