# UK Telnyx number returning Q.850 cause code 17 / User Busy - calls never reach Retell **URL:** \ **Category:** Support Help\ **Tags:** integrations\ **Created:** [April 28, 2026, 9:41am UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501 "2026-04-28T09:41:34Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Euan](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/euan/32/1712_2.png) [@Euan](https://community.retellai.com/u/Euan)\ **Post date:** [April 28, 2026, 9:41am UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501/1 "2026-04-28T09:41:34Z")
UK Telnyx number returning Q.850 cause code 17 on all inbound calls. Calls appear in Telnyx CDRs but never show in Retell call history. Setup: FQDN connection, [sip.retellai.com](http://sip.retellai.com) SRV, Europe region, TCP, +E.164 format. Credentials set up in Telnyx outbound auth and matching in Retell SIP trunk settings. Termination URI sip.telnyx.eu. Agent is published and assigned. Has anyone got a UK Telnyx number working with Retell? What am I missing?" ---
**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\ **Post date:** [April 28, 2026, 1:10pm UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501/2 "2026-04-28T13:10:15Z")
Hey @Euan Could you please share the call IDs along with their PCAP files? This will help our team investigate the issue more effectively. Thank you! ---
**Author:** ![Euan](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/euan/32/1712_2.png) [@Euan](https://community.retellai.com/u/Euan)\ **Post date:** [April 29, 2026, 8:05pm UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501/3 "2026-04-29T20:05:51Z")
Hey Mark, Thanks for your reply. Here are three of my recent Telnyx call IDs: 51684118-4406-11f1-b857-02420aefde20 a45d7f1e-4307-11f1-bb13-02420aef9820 dcfe77f0-42e5-11f1-85fc-02420aef9620 I’m unable to generate PCAP files — the Call Data Debugging is greyed out on my account. Can you work with these IDs or advise another way to get you the data you need? Thanks! ---
**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\ **Post date:** [April 29, 2026, 8:07pm UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501/4 "2026-04-29T20:07:30Z")
Hello @Euan Thank you for the details. I’ve forwarded them to our team for review. We’ll get back to you as soon as we have an update. Best regards ---
**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\ **Post date:** [April 29, 2026, 8:47pm UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501/5 "2026-04-29T20:47:59Z")
Hey @Euan Could you please share your organization ID and the phone number in question? We’ll check whether it has been imported and configured correctly. Thank you! ---
**Author:** ![Euan](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/euan/32/1712_2.png) [@Euan](https://community.retellai.com/u/Euan)\ **Post date:** [April 30, 2026, 6:30pm UTC](https://community.retellai.com/t/uk-telnyx-number-returning-q-850-cause-code-17-user-busy-calls-never-reach-retell/2501/6 "2026-04-30T18:30:15Z")
Hey @mark1 Thanks, by organization ID do you mean my Retell workspace ID? If so, Workspace ID: org\_7vrP28pjS1qdwfjY The phone number is: +44(139)271-8720 Thanks for your help!\*\*