Even at the RFC 4028 minimum interval of 90 seconds, a missed refresh ends the call at about 60 seconds (90 minus the smaller of 32 and 30 seconds). A standards-conformant session-timer failure therefore cannot, on its own, explain a drop at about 30 seconds. Session-timer drops usually appear at 15 or 30 minutes.

inferred · Checked 2026-09-25

Vendor
IETF
Product
SIP
Subsystem
troubleshooting
Deployment
any
Region
not restricted
Release range
RFC 4028 conformant implementations
Status
inferred
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-session-timer-not-30s. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-session-timer-not-30s

BibTeX

@misc{warmtransfer-claim-sip-calls-drop-30-seconds-session-timer-not-30s,
  title  = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-session-timer-not-30s},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-session-timer-not-30s},
  note   = {Source note sip-calls-drop-30-seconds-session-timer-not-30s, checked 2026-09-25}
}

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