Source note · SIP call forwarding and routing loops
RFC 5393 does not change RFC 3261's recommended initial Max-Forwards value of 70; it mitigates the amplification that this depth allows by adding loop-detection and Max-Breadth requirements.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- Max-Forwards
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 5393 onward
- Checked
- 2026-09-25
Sources
- RFC 5393: Addressing an Amplification Vulnerability in Session Initiation Protocol (SIP) Forking Proxies — IETF / RFC Editor · tier 1 standards and regulators · Section 3 (Vulnerability) and Section 4 discussion of Max-Forwards
Cite this note
APA
WarmTransfer. (2026, September 25). SIP call forwarding and routing loops: source note sip-forwarding-loops-rfc5393-keeps-70. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-rfc5393-keeps-70
BibTeX
@misc{warmtransfer-claim-sip-forwarding-loops-rfc5393-keeps-70,
title = {SIP call forwarding and routing loops: source note sip-forwarding-loops-rfc5393-keeps-70},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-rfc5393-keeps-70},
note = {Source note sip-forwarding-loops-rfc5393-keeps-70, checked 2026-09-25}
}