Under RFC 4028 the refresher sends its session refresh once half the session interval has elapsed.

Checked 2026-09-25

Vendor
IETF
Product
SIP
Subsystem
session timers
Deployment
any
Region
not restricted
Release range
RFC 4028
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-refresh-half-interval. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-refresh-half-interval

BibTeX

@misc{warmtransfer-claim-sip-calls-drop-30-seconds-refresh-half-interval,
  title  = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-refresh-half-interval},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-refresh-half-interval},
  note   = {Source note sip-calls-drop-30-seconds-refresh-half-interval, checked 2026-09-25}
}

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