I'm running into a problem when using Telnyx with Vapi. During call transfers, Vapi sends the customer’s phone number instead of my Telnyx number as the caller ID, and Telnyx rejects the transfer because the “from” number isn’t one of my verified numbers. How do I fix that?

To fix the caller ID issue with Telnyx transfers, switch to the SIP integration and set your transfer destination using a SIP URI. Here’s an example configuration for your transfer tool:

json
{
  "type": "transferCall",
  "destinations": [
    {
      "type": "sip",
      "sipUri": "sip:+1234567890@sip.telnyx.com"
    }
  ]
}

Make sure SIP REFER is enabled in your Telnyx account for transfers to work properly. For more details, see the [Telnyx SIP integration guide](https://docs.vapi.ai/advanced/sip/telnyx). Source: - [Vapi SIP Trunking Telnyx documentation](https://docs.vapi.ai/advanced/sip/telnyx)

Hi Moe, To troubleshoot call transfer issues with Telnyx using Vapi, please follow the steps outlined in the [Debug Call Forwarding Drops](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops) guide. Here's a concise list of steps to consider: 1. **Verify Vapi Call Forwarding**: Use the provided cURL command or SDK sample to check if Vapi initiated the forwarding. Ensure the

endedReason

is

"assistant-forwarded-call"

. 2. **Configuration Check**: - Ensure the

phoneCallProviderBypassEnabled

is set to

false

unless you have a specific use for custom call control. - Review your assistant's server message settings; remove

"phone-call-control"

if present unless custom logic is implemented. 3. **Supported Transfers**: Check the transfer scenario to ensure it's supported (e.g., phone to phone is supported). 4. **Analyze Telephony Provider**: - Retrieve the

phoneCallProviderId

from the call object. - For Telnyx, examine the call logs for transfer-related errors and ensure configuration aligns with the [Telnyx SIP Integration](https://docs.vapi.ai/advanced/sip/telnyx) guide. 5. **SIP Packet Analysis**: If issues persist, use Wireshark to analyze SIP signaling: - Download the PCAP file if available and look for REFER packets. 6. **Common Solutions**: - Confirm correct format and availability of the destination number. - Test direct calls to the destination number outside of Vapi. For setup, follow the [Telnyx SIP Integration Guide](https://docs.vapi.ai/advanced/sip/telnyx) for inbound/outbound configurations and ensure the authentication details and number associations are correctly set in Vapi. If you have completed these steps and the issue persists, further analysis on configuration errors or potential limitations is advised. If this doesn’t resolve the issue, please let us know and we’ll be happy to step in and assist further.