# Inbound calling issue **URL:** \ **Category:** Support Help\ **Tags:** telephony\ **Created:** [May 17, 2026, 11:04am UTC](https://community.retellai.com/t/inbound-calling-issue/2741 "2026-05-17T11:04:26Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 17, 2026, 11:04am UTC](https://community.retellai.com/t/inbound-calling-issue/2741/1 "2026-05-17T11:04:27Z")
Hi Retell Support Team, I am experiencing an issue with inbound calling on my imported Telnyx number. Current situation: - When Termination SIP URI is set to [sip.telnyx.com](http://sip.telnyx.com/) → Outbound calls work fine, but inbound calls return busy (486) - When Termination SIP URI is set to [retell-ai-clinic.sip.telnyx.com](http://retell-ai-clinic.sip.telnyx.com/) (my specific Telnyx subdomain) → Inbound still returns busy AND outbound stops working entirely Setup details: - Provider: Telnyx Elastic SIP Trunk - SIP Connection: retell-ai-clinic - Number: +16674218313 - FQDN in Telnyx:(SRV record) ✓ - Inbound agent: assigned and published ✓ - Codecs: G722, G711U, G711A ✓ - Transport: TCP ✓ - SIP Region: Asia (Beta) ✓ The inbound call never appears in Retell Call History, which suggests the call is not reaching Retell at all. Could you please advise on the correct configuration to get inbound calls working? Thank you. ---
**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:** [May 18, 2026, 3:04pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/2 "2026-05-18T15:04:02Z")
Hello @ali.desndev your inbound issue is on the Telnyx side, not the termination SIP URI. The Termination SIP URI in Retell should remain `sip.telnyx.com` (or your region-localized Telnyx FQDN) — that’s only used for outbound. That’s why switching it to your subdomain breaks outbound. For inbound to reach Retell, in Telnyx you need: 1. FQDN added to the trunk = `sip.retellai.com` with SRV as the DNS record type (this is what routes inbound to Retell). 2. The number must be assigned/moved to this trunk. 3. Inbound settings: +E.164 number format, codecs G722, G711U, G711A, transport TCP, and your SIP region selected. A 486 Busy on inbound that never reaches Retell Call History usually means Telnyx isn’t forwarding the call to `sip.retellai.com` — verify the FQDN entry ([sip.retellai.com](http://sip.retellai.com), SRV) is on the trunk and the number is attached to that same trunk. Also make sure the number has an inbound agent assigned in Retell. ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 18, 2026, 4:21pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/4 "2026-05-18T16:21:17Z")
Hi Team, We have completed extensive debugging and confirmed the following: - Telnyx is successfully sending the INVITE to `sip.retellai.com` - Retell immediately responds with `486 User Busy` - The call never appears in Retell Call History We have already verified: - FQDN configured as `sip.retellai.com` (SRV) - Inbound agent assigned and published - TCP transport enabled - SIP region set to Asia (Beta) - Correct codecs enabled - Phone number attached to the correct trunk - Retell termination URI set to `sip.telnyx.com` At this point, the INVITE is clearly reaching Retell but being rejected before the call is registered in the dashboard. Could you please check whether there is an issue with: 1. Our specific Retell account 2. The Asia (Beta) SIP region handling inbound calls Workspace email: [ali.desndev@gmail.com](mailto:ali.desndev@gmail.com) Thank you. ---
**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:** [May 18, 2026, 4:22pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/5 "2026-05-18T16:22:10Z")
Hey @ali.desndev Can you send your workspace ID and your Agent ID ? ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 18, 2026, 4:28pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/6 "2026-05-18T16:28:53Z")
Workspace ID : org\_p6aQHfuVADccyCMI Agent ID : agent\_84a95d088b62b9db971d170a42 ---
**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:** [May 18, 2026, 4:32pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/7 "2026-05-18T16:32:29Z")
@ali.desndev Ok i check with the team on this ---
**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:** [May 18, 2026, 6:05pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/8 "2026-05-18T18:05:47Z")
Hey @ali.desndev The 486 is being returned upstream of Retell (almost certainly by Telnyx, most commonly: DID not assigned to the FQDN trunk, or Asia anchor site rejecting an out-of-region +1 NANP inbound). Could you please pull a Telnyx “SIP Call Flow” debug export for one failing inbound attempt? That will show exactly which Telnyx node returned the 486 and the Q.850 cause. Thank You ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 18, 2026, 6:36pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/9 "2026-05-18T18:36:00Z")
Hi Team, I’m unable to access a detailed SIP Call Flow debug export for inbound calls from the Telnyx dashboard. Telnyx is only showing the call logs on my side. Based on the available logs, I can confirm the following: - Q.850 Cause Code: 17 - Termination LRN: 6674021999 The logs still show the INVITE reaching `sip.retellai.com` and then receiving `486 User Busy`. And I am using the Pakistani number for inbound; however, the outbound is working perfectly with the Pakistani number Please let me know if there is any other specific information you would like me to collect from the Telnyx logs. Thank you. ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 19, 2026, 2:07pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/10 "2026-05-19T14:07:55Z")
Hi Team! Yesterday we discussed the issue, now we are waiting for your response Please let me know once you have configured it. It will be really appreciated! 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:** [May 19, 2026, 2:22pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/11 "2026-05-19T14:22:24Z")
Hey @ali.desndev Your issue has been already send to the team, once received a reply i will get back to you. ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 20, 2026, 3:50pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/12 "2026-05-20T15:50:00Z")
Hi, just following up on this issue. Any update from the team regarding the configuration? Please let us know once it’s done. 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:** [May 20, 2026, 5:44pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/13 "2026-05-20T17:44:15Z")
Hey @ali.desndev could you please share a screenshot of the Telnyx call detail showing the 486 response and the `Via` headers that can help us confirm whether the 486 originated from our SBC or a Telnyx-internal hop. In the meantime as a quick A/B, can you temporarily switch the SIP region from Asia (Beta) to a GA region (US or EU) and place one inbound test. Thank You ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 20, 2026, 6:48pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/14 "2026-05-20T18:48:08Z")
![Screenshot 2026-05-20 at 11.37.31 PM](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/2X/c/cbda0321bc450f17c3eab0d412cff65ad66359ec.jpeg) ![Screenshot 2026-05-20 at 11.37.50 PM](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/2X/7/7fffb9951ea8498e34378e534e7a53f4c372f4e2.png) ![WhatsApp Image 2026-05-20 at 11.43.40 PM](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/2X/6/63d70cc901e86dd0301aaee61b355caad62477b7.jpeg) Hi, I have attached the screenshots including the Via headers. I also changed the SIP region to US and tested again with an inbound call, but it is still returning a busy response (486), line busy. 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:** [May 21, 2026, 1:19pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/15 "2026-05-21T13:19:17Z")
Hey @ali.desndev So, this confirms the issue is on the inbound binding of this DID inside your Telnyx account. Your outbound is fine because it uses a separately-configured Outbound Voice Profile. Can you check voice settings for this number. ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 21, 2026, 2:03pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/16 "2026-05-21T14:03:25Z")
![Screenshot 2026-05-21 at 7.01.30 PM](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/2X/0/0c502c2420093ea73fbbe2b24a2041c4888c2acc.png) ![Screenshot 2026-05-21 at 7.02.05 PM](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/2X/4/4d9ab6e0565080d93ef531c0792182de67152c60.jpeg) ![Screenshot 2026-05-21 at 7.02.21 PM](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/2X/f/f25d72e85a96ecabe4f613644aa3e0cc85fabc60.png) Hi, I have attached the screenshots for reference. These confirm that our DID is properly assigned to the SIP connection, the SIP connection is correctly configured on the number, and the inbound settings are also configured correctly. We have also reviewed the authentication credentials (username/password) multiple times and they are correct. Additionally, on the Telnyx side, the call logs/history show that the inbound call is received and forwarded successfully from Telnyx. This makes it appear that the issue may be on the Retell side, where the call is either not being identified correctly or not being accepted/answered properly. Could you please check this further from your side? 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:** [May 21, 2026, 2:13pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/17 "2026-05-21T14:13:20Z")
Hey @ali.desndev Checking with team. ---
**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:** [May 21, 2026, 6:36pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/18 "2026-05-21T18:36:09Z")
Hey @ali.desndev The SIP auth credentials are not relevant to this failure, those username/password fields authenticate Retell → Telnyx (outbound) traffic, which is why your outbound works. The screenshots you sent confirm the DID is assigned to the `retell-ai-clinic` SIP Connection (good), and the Voice and Numbers tabs are configured. But the missing piece is on a different tab. Can you share Authentication and routing tab? in the dm to me not here here you’ll see Connection Type: Credentials / IP / FQDN. For Retell, this must be set to FQDN, and the FQDN list must contain: [sip.retellai.com:5060](http://sip.retellai.com:5060);transport=tcp If it’s currently set to Credentials, that is the bug, Telnyx is waiting for Retell to REGISTER (we don’t; we’re a static FQDN SBC), so it has no Address-of-Record to forward calls to and returns cause 17. If it’s already FQDN but the list is empty or contains a leftover host from a previous integration, that’s the same outcome. Thank You ---
**Author:** ![ali.desndev](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/ali.desndev/32/1178_2.png) [@ali.desndev](https://community.retellai.com/u/ali.desndev)\ **Post date:** [May 22, 2026, 10:34am UTC](https://community.retellai.com/t/inbound-calling-issue/2741/19 "2026-05-22T10:34:09Z")
Hi, I have sent you a DM with all the details and screenshots. Could you please check your inbox when you get a chance? Thank you! ---
**Author:** ![andrew5](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/andrew5/32/1986_2.png) [@andrew5](https://community.retellai.com/u/andrew5)\ **Post date:** [May 23, 2026, 12:53am UTC](https://community.retellai.com/t/inbound-calling-issue/2741/20 "2026-05-23T00:53:24Z")
Hey @ali.desndev Were you able to get this resolved? If not, feel free to reach out, I work on the Retell Telephony team and would love to assist you. ---
**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:** [May 25, 2026, 7:56pm UTC](https://community.retellai.com/t/inbound-calling-issue/2741/21 "2026-05-25T19:56:47Z")
Hey @ali.desndev From the info you gave us and checking on our side, there isn’t anything we can do on our side but you should contact Telnyx why The Terminating LRN `6674021999` does not match your DID’s NPA-NXX (`667-421`). Could you open a ticket with Telnyx support stating: “Inbound calls to `+16674218313` on my account return 486 / Q.850 cause 17 with Terminating LRN `6674021999` (doesnt match NPA-NXX). Direction=Inbound CDRs are recorded but no INVITE leaves your network toward my configured FQDN (`sip.retellai.com`). Please verify the inbound number-to-Connection binding for this DID and provide a SIP Call Flow for a failing attempt showing which Telnyx node generated the 486.” Thank You