Hi,
I’m facing issue with inbound call for Retell with Telnyx phone number. My outbound call is working fine, but when trying to do inbound call, it is not connecting at all. No log is showing in Retell call history or Telnyx troubleshooting. It is showing busy always. The setup looks correct for FQDN.
My SIP trunking connection: Telnyx Customer Portal
Can anyone please help?
Nothing in Retell’s call history usually means the call is being rejected at the SIP layer before Retell creates a call record. Outbound working only proves your credentials and outbound voice profile are right. Inbound is a separate path.
Three things to check, in order.
Is the number actually assigned to that SIP connection in Telnyx? Open it under Numbers and confirm Connection points at your elastic trunk. Telnyx showing nothing in troubleshooting points here hardest, because the call never leaves via the trunk.
Is the number imported into Retell with an inbound agent bound to it? Outbound works without that, inbound does not. If anything was off at import, delete it and import again.
Then check the inbound number format on the connection. It has to be +E.164. If Telnyx sends national format, Retell will not match it against your imported number.
If all three look right, pull the SIP response code for one failed call from the Telnyx debugging tool. A 486 sends you back to points two and three. No leg at all means it is not getting out of Telnyx.
One caveat: the docs cover the setup steps but do not spell out what Retell does with a To number it does not recognise. That bit is my read from an earlier thread with the same symptom, so treat it as a check rather than gospel.
Russell
amplifyautomation.ai
I’ve checked. All set. One thing, I am trying to call a US number from India. So should the US phone number bought from Telnyx should be Toll-free?
No, do not go toll-free. It would probably make it worse. US toll-free numbers are usually not dialable from outside the US and Canada, since most international carriers either block them or have no route for them. A standard US local number takes inbound calls from India without any problem, so the number type is not your issue.
That said, your question changes the picture a bit. If every test call has been made from India, you may be chasing a config problem that is actually an international routing one. Try the number from a US phone, or a US-based softphone, before you touch the trunk again. If it connects from the US and stays busy from India, the trouble is in the path from your Indian carrier to Telnyx, not in your Retell setup.
Also worth confirming your line allows ISD calls and you are dialling the full +1 number in E.164.
Russell
amplifyautomation.ai
Hello @nsen59341
Could you please share your Org ID (Settings → Workspace) and the PCAP file from your provider for the relevant call? This will help us investigate the issue further.
Thank you!
HEy
org_bJNB7JauXkWAZwgv
Hey,
my workspace id is: org_bJNB7JauXkWAZwgv
Unfortunately, I am unable to find the call records for my Indian number, but today I tried using another US Telnyx number, so I am sharing that record.
2026-08-18 15:57:19.607 call_da4702212f2cfa0dd0155a4c67a info: Starting call: call_da4702212f2cfa0dd0155a4c67a
2026-08-18 15:57:22.165 call_da4702212f2cfa0dd0155a4c67a error: Error dialing to user, SIP status code: 486 SIP error category: user_busy Error: twirp error unknown: INVITE failed: sip status: 486: User Busy
To troubleshoot, check out:
2026-08-18 15:57:22.165 call_da4702212f2cfa0dd0155a4c67a info: Ending call: call_da4702212f2cfa0dd0155a4c67a
@nsen59341 Checking it with team.
Hello @nsen59341 thanks for the details. Two separate things going on here, let me separate them:
-
The call you shared (
call_da4702212f2cfa0dd0155a4c67a) is an outbound call, not inbound. The486 User Busycame from the number you dialed (+17792571355) rejecting/being busy on their side. It’s not related to your inbound issue. -
For the actual inbound problem (Indian Telnyx DID hitting busy, no log anywhere): if the call never appears in Retell’s history and not in Telnyx SIP Debugger, the INVITE isn’t leaving Telnyx toward Retell at all. Your Retell-side binding is correct (DID bound to your agent), so the fix is on the Telnyx side. Please check:
- Telnyx Portal → Numbers → My Numbers → your Indian DID: confirm it is assigned to a SIP Connection (not unassigned, not pointed at a TeXML/Call Control app), and the DID is voice-enabled with inbound enabled.
- That SIP Connection → Outbound Voice Profile / Inbound settings: the destination must be
sip.retellai.com. Anything else (including<tenant>.sip.telnyx.com) will not reach Retell. - Telnyx Portal → Debugging → SIP Call Flow: filter by the DID + a fresh test timestamp. If you see no outbound INVITE toward
sip.retellai.com, the failure is entirely Telnyx-side (DID misassignment, Connection disabled, or the DID doesn’t have inbound service in that country). If you do see an INVITE going out and Retell responds with a 4xx/5xx, share that trace and we’ll pick it up from there.
One more control: please run the same inbound test against the US Telnyx DID (+19108985337) so we can isolate whether this is India-specific or all inbound. Share the timestamp of that test either way.
Thank You
Hi
Just ran another inbound test to +1 910 898 5337 - time: 11:21 pm IST.
And I’ve checked all other pointers; those are fine. By filtering my DID and current date range, I’m getting outbound records as well.
Thanks
Hello @nsen59341 Team re-checked the 11:21 PM IST retest and there is still no inbound INVITE landing on Retell for +19108985337 (Retell-side binding to your HVAC Telnyx agent is correct and outbound on that same DID is healthy, so the trunk itself is fine). That means Telnyx isn’t sending the inbound leg to sip.retellai.com.
The record you shared (call_da4702212f2cfa0dd0155a4c67a) is again an outbound call from +19108985337 → +17792571355 that got 486 User Busy from the called party — not related to the inbound issue.
Could you send screenshots from the Telnyx portal for the 11:21 PM IST test:
- Telnyx → Reporting → SIP Call Flow (Debugger): filter by the DID (+19108985337) and the exact minute of the test. You mentioned outbound records show up — please expand the filter to include inbound direction and screenshot what appears (or “no results”). If there is an inbound INVITE, share the SDP/ladder so we can see where it’s being routed.
- Numbers → +19108985337 → Voice settings: screenshot of the “Connection” field (must point to a SIP Connection, not a TeXML/Call Control app).
- That SIP Connection → Outbound Voice Profile settings: screenshot showing the outbound destination FQDN is
sip.retellai.comand inbound is enabled. - Also please retest the Indian DID (the number this ticket is actually about) and share its Telnyx SIP Debugger screenshot for that timestamp — the US number was a substitution, but the original problem is on the IN DID.
If Telnyx SIP Debugger shows no inbound INVITE at all for a fresh test, the block is upstream of Telnyx’s SBC (carrier-side to the DID) and needs a Telnyx support ticket. If it shows an INVITE going anywhere other than sip.retellai.com, the DID’s Connection routing is misconfigured.
Please don’t share any sensitive or confidential information. If you share a screenshot, please blur or hide any sensitive details first.
Thank You