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SIP integration - Unable to receive Inbound calls
# support
g
I’m experiencing an issue with configuring a number connected via SIP. On my Mac, I have no problems initializing a SIP connection and receiving calls through pjsua:
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pjsua --id sip:XXX@XXX.reg.cloud-cfg.com --registrar sip:XXX.reg.cloud-cfg.com --realm '*' --username XXX --password XXX --log-level 4
On VAPI, to proceed with the configuration I carried out only the following steps:
1. Creation of the credentials
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curl --location 'https://api.vapi.ai/credential' \
--header 'Authorization: Bearer xxx' \
--header 'Content-Type: application/json' \
--data '{
    "provider": "byo-sip-trunk",
    "name": "Test SIP",
    "gateways": [
        {
          "ip": "xxxx.reg.cloud-cfg.com",
          "port": 5060,
          "outboundEnabled": true,
          "inboundEnabled": false,
          "outboundProtocol": "udp"
        },
        {
          "ip": "x.x.x.x",
          "port": 5060,
          "outboundEnabled": false,
          "inboundEnabled": true
        }
    ],
    "outboundLeadingPlusEnabled": true,
    "outboundAuthenticationPlan": {
      "authUsername": "XXX",
      "authPassword": "XXX",
      "sipRegisterPlan": { "realm": "xxx.reg.cloud-cfg.com" }
    }
  }'
Response:
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{
  "id": "ffbdd571-61d0-4672-a82e-f286495f3057",
  "orgId": "80b234ee-d7b2-4bde-aa3c-2b53c585d600",
  "provider": "byo-sip-trunk",
  "createdAt": "2025-09-23T06:22:25.448Z",
  "updatedAt": "2025-09-23T06:22:25.448Z",
  "gateways": [
    {
      "ip": "XXX",
      "port": 5060,
      "inboundEnabled": false,
      "outboundEnabled": true,
      "outboundProtocol": "udp"
    },
    {
      "ip": "x.x.x.x",
      "port": 5060,
      "inboundEnabled": true,
      "outboundEnabled": false
    }
  ],
  "name": "Test SIP",
  "outboundAuthenticationPlan": {
    "authUsername": "XXX",
    "sipRegisterPlan": {
      "realm": "XXX.reg.cloud-cfg.com"
    }
  },
  "outboundLeadingPlusEnabled": true
}
2. I save the credential_id and execute the call:
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curl --location 'https://api.vapi.ai/phone-number' \
--header 'Authorization: Bearer XXX' \
--header 'Content-Type: application/json' \
--data '{
    "provider": "byo-phone-number",
    "name": "Test SIP",
    "number": "39XXXXXXXX",   //this is public number associated to SIP credential
    "numberE164CheckEnabled": false,
    "credentialId": "ID_VALUE_FROM_LAST_CALL"
}'
Response:
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{
  "id": "fdf3d4b3-2c3b-4ca7-9a95-67eed0cad897",
  "orgId": "80b234ee-d7b2-4bde-aa3c-2b53c585d600",
  "number": "39XXXX",
  "createdAt": "2025-09-23T06:22:46.459Z",
  "updatedAt": "2025-09-23T06:22:46.459Z",
  "name": "Test SIP",
  "credentialId": "ffbdd571-61d0-4672-a82e-f286495f3057",
  "provider": "byo-phone-number",
  "numberE164CheckEnabled": false,
  "status": "active",
  "providerResourceId": "530ba48c-daed-4102-909d-8409f6699211"
}
When I try to call the phone number connected to the SIP, it doesn’t ring and I don’t see the call on VAPI. Since I successfully completed an inbound test on my Mac, I’m sure that something is missing in the procedure on VAPI.
v
Thanks for sharing your setup! To help troubleshoot, could you specify which SIP provider you’re using with Vapi and whether you’ve configured your provider to forward inbound calls to the correct SIP URI (e.g., 
{phoneNumber}@<credential_id>.sip.vapi.ai
)? This will help pinpoint where the inbound routing might be failing. Tip: Double-check that you’ve allowlisted Vapi’s IPs (
44.229.228.186/32
, 
44.238.177.138/32
) in your provider’s settings for SIP signaling and media, as missing this step can block inbound calls. Let me know the provider and your current forwarding setup! Source: - [SIP Trunking – Vapi Documentation](https://docs.vapi.ai/advanced/sip/sip-trunk)
g
Thanks @Lordvickthor for your time. How could I check if inbound route work properly?
g
Some one here?? @Vapi @Vapi Support Bot
v
Suggestion: Double-check that your SIP provider is forwarding inbound calls to the correct SIP URI in this format:
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{yourPhoneNumber}@{yourCredentialId}.sip.vapi.ai
For example, if your number is 
39123456789
and your credential ID is 
ffbdd571-61d0-4672-a82e-f286495f3057
, the SIP URI should be:
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39123456789@ffbdd571-61d0-4672-a82e-f286495f3057.sip.vapi.ai
Update your provider's inbound routing to use this SIP URI, then test again. Reference: [Vapi SIP Trunking Inbound Call Test](https://docs.vapi.ai/advanced/sip/sip-trunk#inbound-call-test) Source: - [SIP Trunking – Vapi Documentation](https://docs.vapi.ai/advanced/sip/sip-trunk)
c
Hi gio, If you're experiencing issues with SIP trunking, we recommend reviewing the SIP provider integration documentation specific to your provider, such as [Plivo](https://docs.vapi.ai/advanced/sip/plivo), [Twilio](https://docs.vapi.ai/advanced/sip/twilio), or [Telnyx](https://docs.vapi.ai/advanced/sip/telnyx). Ensuring proper configuration, including correct IP whitelisting and authentication setup, is crucial. For inbound call issues, make sure your provider forwards calls to the correct SIP URI (e.g., 
{phoneNumber}@<credential_id>.sip.vapi.ai
) and that the Vapi-related IPs are whitelisted on your SIP provider's platform. Outbound call problems might require checking the correct use of credential IDs, phone numbers, and ensuring network configurations align with Vapi’s requirements. For specific error codes like 
call.in-progress.error-sip-outbound-call-failed-to-connect
, issues often relate to connectivity or misconfigurations between Vapi and your SIP provider. Detailed error codes can be reviewed in the [Call Ended Reasons](https://docs.vapi.ai/calls/call-ended-reason) documentation, which may highlight potential troubleshooting steps based on the encountered error during a call. Feel free to reach out if you need more detailed guidance or further assistance. If this doesn’t resolve the issue, please let us know and we’ll be happy to step in and assist further.
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