The first diagnostic step for a suspected missing ACK is a SIP capture showing whether the ACK actually reaches the callee device. Then check that the Contact in the 200 OK carries an address the caller side can reach.

field report · Checked 2026-09-25

Vendor
OpenSIPS
Product
SIP (general)
Subsystem
troubleshooting
Deployment
any
Region
not restricted
Release range
as of 2017
Status
field report
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-first-check-ack-arrives. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-first-check-ack-arrives

BibTeX

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

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