Telnyx outbound call error: 422
# supportá
Ábel Zoltán
03/27/2025, 3:48 PMHello guys! I have a configured Telnyx SIP trunk working well for outbound calls. I can initiate outbound calls to my hungarian phone number using Zoiper SIP client. I also integrated this SIP trunk into VAPI. A tried to initiate an out bound call using VAPi UI, but got this error: Couldn't Make Telnyx Call. Error: Request failed with status code 422. See the attached screenshot.
I also tried to initate an outbound call using VAPI API. This is my request content:
{
"assistantId": "9a7be519-b4b0-4f5e-ac0f-9dc5814feb04",
"customer": {
"number": "124436202885573",
"numberE164CheckEnabled": false
},
"phoneNumberId": "1dd459c3-f3a0-47b0-8a1c-7585997f877d"
}
The response is the same: Couldn't Make Telnyx Call. Error: Request failed with status code 422
It seems to me this is an issue between VAPI and Telnyx. Could you please check this? I send the request to VAPI API at 27.03.2025 16:48 (UTC + 01:00)
Thanks for helping!
https://cdn.discordapp.com/attachments/1354844538283495594/1354844538585219184/image.png?ex=67e6c4cd&is=67e5734d&hm=8794cb089254881640498a97243f5cb766759f851c11e0d3026b99b89b0b69a8&
v
Vapi Support Bot
03/27/2025, 3:50 PMI see you're having trouble with the Telnyx outbound call through VAPI. Based on your request and the error message, I'd like to check a few things about your configuration:
1. I notice your API request includes
"number": "124436202885573"phoneNumberIdnumberE164CheckEnabledtruefalseVapi Support Bot
03/27/2025, 3:50 PMHi there! 👋 I see you're having trouble with outbound calls through your Telnyx SIP trunk when using VAPI.
I'm unable to check the specific request you sent at the time mentioned, but I can definitely help troubleshoot the HTTP 422 error you're experiencing with Telnyx outbound calls.
Based on the information you've provided, here are some potential causes and troubleshooting steps:
### Phone Number Format
The most likely issue is with the phone number format. For Telnyx integration with VAPI:
- Ensure your tech prefix is being used correctly. According to the [Telnyx integration documentation](https://docs.vapi.ai/advanced/sip/telnyx), the phone number with the tech prefix should look like "12346699999999" (no + sign).
- In your API request, you're using "124436202885573" - check if "1244" is your tech prefix and if the rest is your Hungarian number.
### International Number Limitations
- A Vapi number can only call US and Canada numbers by default. Since you're trying to call a Hungarian number, this could be causing the 422 error.
### Configuration Checks
- Verify that your Telnyx SIP trunk is correctly configured in VAPI with the proper Credential ID, IP/Port, and Authentication details.
- Check the "Authentication and Routing tab of your SIP Trunking Connection" in Telnyx.
- Ensure that SIP Register is enabled with the proper Domain and Realm.
### API Request Parameters
For your API request, verify:
- The
numberE164CheckEnabledassistantIdphoneNumberIdnameVapi Support Bot
03/27/2025, 3:50 PMWould you like me to provide more specific guidance on any of these areas, or do you have any additional information about the error that might help narrow down the issue?
Sources:
- [Telnyx integration documentation](https://docs.vapi.ai/advanced/sip/telnyx)
- [Discord thread on HTTP 422 error](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1335869152535121960)
- [Discord thread on SIP trunk configuration](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1333747605628391434)
- [Discord thread on international number limitations](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1336713212233515089)
á
Ábel Zoltán
03/29/2025, 8:52 AMYes, the phone numnber I initiate the call to is +36202885573. My telnys prefix is 1244, so I thinkm that I send the request correctly.
SIP trunk for outbound calls in Telnyx works. I tested it with a SIP client, I can call my hungarian phone number
Yes, I have voice profile set in Telnyx.
I tried the numberE164CheckEnabled parameter set to true but the result is the same.
In my Telnyx setup I also enabled the IP addresses of VAPI.
It is still not working initate an outbound call using Telnyx number although all setup is correct. Can you check the 422 status code between VAPI and Telnyx?
k
Kyle Brunker
03/30/2025, 6:38 AMHey Ábel, you just have to delete your number and then import it again. After that, it will work as expected.
á
Ábel Zoltán
04/01/2025, 9:57 PMThanks, I tried several ways to create credentials on API / SIP trunk on UI / add phone numbers using different credentials on API / add phone numbers on UI. Finally my problem is solved on Telnyx side. Although I had valid settings on Telnyx ( I can use the SIP trunk by SIP client) it was not enough for VAPI. I had to create a Voice API application and assign the numbers to it. VAPI started working from that point.
k
Kyle Brunker
04/01/2025, 10:17 PMÁbel, sorry for your experience and hassle, but happy for you - it's working!
s
stevechef_
04/02/2025, 5:30 PMSzia! Én is a Telnyx-el vesződök, nem tudom API kulccsal native módon hozzáadni a Vapihoz. Kérlek tudnál segíteni?
k
Kyle Brunker
04/06/2025, 12:38 PMHi, checking if this is resolved/solved for you?
á
Ábel Zoltán
04/07/2025, 9:33 AMHi, thanks it is resolved. I modified the tag.
k
Kyle Brunker
04/07/2025, 3:58 PMMarking this ticket as Solved ✅
s
steffenxyz_
05/01/2025, 5:00 PM@Ábel Zoltán how exactly did you manage to solve this in telnyx? I am facing the same issue at the moment. Would be super grateful for any hint
á
Ábel Zoltán
05/06/2025, 4:24 PMI wrote it in a previous message: "Although I had valid settings on Telnyx ( I can use the SIP trunk by SIP client) it was not enough for VAPI. I had to create a Voice API application and assign the numbers to it. VAPI started working from that point."
Anyway try to delete your VAPI phone number and reassign it to VAPI. But first try to make the Telnyx side changes.
s
steffenxyz_
05/06/2025, 4:39 PMthank you so much! I will try this