I'm experiencing an issue creating a SIP trunk credentials with Telnyx on my account (Org ID: 339cafe4-8428-482a-9987-c5d5e5be36f5). Problem: When I try to create a SIP trunk credentials with both "Allow inbound calls" and "Allow outbound calls" enabled, I get the error: "Failed to create SIP trunk credentials." What I discovered: - When I DISABLE "Allow inbound calls" → trunk creates successfully - When I ENABLE "Allow inbound calls" → creation fails Additional context: - I have another Vapi account where the EXACT same Telnyx configuration works perfectly with both inbound and outbound calls enabled - Telnyx side is configured identically (credentials authentication, FQDN: sip.vapi.ai:5060, proper inbound routing) - The issue only occurs on this specific Vapi account - account age: 1.5+ years Could you please check if there's an account-level restriction or configuration issue preventing inbound SIP trunk creation?

Hi Marcello, To integrate your Telnyx SIP trunk with Vapi, follow these steps: 1. **Create SIP Trunk Credential**:Use the Vapi API to create a SIP trunk credential:

bash
   curl -X POST https://api.vapi.ai/credential \
   -H "Content-Type: application/json" \
   -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
   -d '{ 
     "provider": "byo-sip-trunk", 
     "name": "Telnyx Trunk", 
     "gateways": [ 
       { "ip": "sip.telnyx.com", "inboundEnabled": false } 
     ], 
     "outboundAuthenticationPlan": { 
       "authUsername": "YOUR_SIP_USERNAME", 
       "authPassword": "YOUR_SIP_PASSWORD",
       "sipRegisterPlan": { "realm": "sip.telnyx.com" } 
     } 
   }'

Replace

YOUR_VAPI_PRIVATE_KEY

,

YOUR_SIP_USERNAME

, and

YOUR_SIP_PASSWORD

with your credentials. 2. **Configure Telnyx Account**:Go to the [Telnyx Portal](https://portal.telnyx.com/#/outbound-profiles) to set up or select the outbound voice profile. Under "Connections and Applications," add Vapi. 3. Assign Numbers: - Navigate to the Vapi dashboard to assign your numbers. Go to the Phone Numbers tab and configure inbound and outbound settings for your voice assistant. 4. **Allowlist Vapi IPs**:Ensure all necessary IPs are allowlisted for SIP traffic:

44.229.228.186/32

and

44.238.177.138/32

. These steps should help establish the Telnyx SIP integration with Vapi. For additional details, refer to the [Telnyx SIP integration guide](https://docs.vapi.ai/advanced/sip/telnyx). If you encounter issues, checking your API request for correct credential inputs often resolves setup errors.

But why "inboundEnabled": false?

You cannot have inbound and outbound enabled on the same gateway. You can have two gateways configured for one BYO SIP trunk, but each gateway must only have one type: inbound or outbound.

So why on other account I have managed to create both inbound and ooutbound on one gateway and it works? https://cdn.discordapp.com/attachments/1440668477303160955/1442415958319956140/Screenshot_2568-11-24_at_14.25.26.png?ex=69255a0b&is=6924088b&hm=65fa371eb9f2276f9679c1dd1179ea5ce3c653d6d8ad42768d59193e3ef4bf8e&

It can be configured for both directions if the static IP address of the trunk's domain is used. Telnyx can be special in this way since we largely support their integration. There was an issue with un-registering trunks that was fixed recently so if you continue to experience a disconnecting SIP trunk, let us know and we'll look at it.