# Outbound SIP call remains ringing after answer — provider receives no ACK after 200 OK

**URL:** <https://community.livekit.io/t/outbound-sip-call-remains-ringing-after-answer-provider-receives-no-ack-after-200-ok/1847>\
**Category:** Telephony\
**Tags:** sip-other-provider, sip-trunking\
**Created:** [August 12, 2026, 1:29am UTC](https://community.livekit.io/t/outbound-sip-call-remains-ringing-after-answer-provider-receives-no-ack-after-200-ok/1847 "2026-08-12T01:29:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Yu\_Zhang](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/yu_zhang/32/2199_2.png) [@Yu\_Zhang](https://community.livekit.io/u/Yu_Zhang)\
**Post date:** [August 12, 2026, 1:29am UTC](https://community.livekit.io/t/outbound-sip-call-remains-ringing-after-answer-provider-receives-no-ack-after-200-ok/1847/1 "2026-08-12T01:29:26Z")

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Hi LiveKit team,

We’re debugging an outbound SIP call through Photon/Spectrum.

The recipient answered, but LiveKit remained at **sip.callStatus=ringing.**  
CreateSIPParticipant(wait\_until\_answered=True) eventually returned HTTP 408, so our TTS never started.

Photon checked its server-side SIP trace and confirmed:

- The carrier sent 200 OK at 2026-08-11 17:50:44.663 UTC
- Photon forwarded it to LiveKit at 17:50:44.664 UTC
- Photon did not receive an ACK
- After approximately 32 seconds without an ACK, Photon terminated the call with BYE

Call details:

- LiveKit SIP Call ID: SCL\_WvjPdttCtPMQ
- Room ID: RM\_gCPi4nwNhHig
- Photon-side Call-ID: epBue8Uzc1dMefx6Mn3ljf3BmRSG
- Caller ID: +1 628-488-4084
- Destination: ending in 2278
- Trunk: TLS to sip.spectrum.photon.codes:5061
- Codec: PCMU/8000 + telephone-event

We verified that the LiveKit outbound trunk address, TLS transport, digest credentials, and caller ID are configured correctly.

Could you please check:

1. Did LiveKit receive the 200 OK?

2. Did LiveKit generate an ACK, and to which IP, port, Request-URI, and transport was it sent?

3. Did the Contact or Record-Route headers affect ACK routing?

4. Could you inspect or share the PCAP for this call?

Thanks!

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**Author:** ![darryncampbell](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/darryncampbell/32/20_2.png) [@darryncampbell](https://community.livekit.io/u/darryncampbell)\
**Post date:** [August 12, 2026, 3:11am UTC](https://community.livekit.io/t/outbound-sip-call-remains-ringing-after-answer-provider-receives-no-ack-after-200-ok/1847/2 "2026-08-12T03:11:06Z")

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Hi, I see an error in the server logs indicating we are not receiving audio packets.

This is most typically a firewall or network issue, can you please review the firewall info at [Configuring firewalls | LiveKit Documentation](https://docs.livekit.io/deploy/admin/firewall/) ?

The call did not generate a PCAP on our end but I see server logs that imply we received the 200 OK.

I don’t have a log that the ACK was generated, but it would have been. Though, without a pcap, I can’t say where it was sent. It looks like both ends gave up, since we also gave up as we had no media.

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**Author:** ![system](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/system/32/26_2.png) [@system](https://community.livekit.io/u/system)\
**Post date:** [August 27, 2026, 3:11am UTC](https://community.livekit.io/t/outbound-sip-call-remains-ringing-after-answer-provider-receives-no-ack-after-200-ok/1847/3 "2026-08-27T03:11:57Z")

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