Source note · Calls that drop after about 30 seconds
A common cause of a missing ACK is a proxy that does not handle a NATed callee: the callee's private IP stays in the Contact of the 200 OK, so the ACK is sent to an address it cannot reach.
field report · Checked 2026-09-25
- Vendor
- OpenSIPS
- Product
- SIP proxies (general)
- Subsystem
- NAT traversal
- Deployment
- any
- Region
- not restricted
- Release range
- as of 2017
- Status
- field report
- Checked
- 2026-09-25
Sources
- Troubleshooting missing ACK in SIP — OpenSIPS Project · tier 4 archived vendor documentation · Section on root causes: 'No NAT Handling'
Cite this note
APA
WarmTransfer. (2026, September 25). Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-nat-private-contact. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-nat-private-contact
BibTeX
@misc{warmtransfer-claim-sip-calls-drop-30-seconds-nat-private-contact,
title = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-nat-private-contact},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-nat-private-contact},
note = {Source note sip-calls-drop-30-seconds-nat-private-contact, checked 2026-09-25}
}