We are going to connect an external VPBX via SIP with VAPI, we know that it is done through SIP Trunk, The objective is that when someone calls the PBX, the call is routed to VAPI and an attendant is activated. Is this feasible? We would need to add a number of IPs to allow traffic without possible blocking. We need it to receive calls and route them to an attendant, such as making outbound calls to other phones after the call is finished. Thanks for your help

Yes, it is feasible to connect your external VPBX with VAPI using SIP trunking to route calls and activate an attendant. Here’s a brief overview of the steps you need to follow: 1. **Network Requirements**: Ensure you add the following VAPI IP addresses to your allowlist to avoid traffic blockage: -

44.229.228.186/32

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44.238.177.138/32

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172.31.9.106/32

2. **Set Up SIP Trunk on VAPI**: - Obtain your SIP provider details, such as server address and authentication credentials. - Create a SIP trunk credential in VAPI: Use the VAPI API to create a new credential with your SIP provider's information. - Associate a phone number with this SIP trunk by creating a Phone Number resource in VAPI. 3. **Testing**: - Test your setup by making outbound calls through the VAPI dashboard or API to ensure everything is routing correctly. - If inbound routing is configured, verify by calling your associated phone number from an external line. For detailed steps and examples, refer to the [SIP Trunking Guide](https://docs.vapi.ai/advanced/sip/sip-trunk). Once set up, incoming calls to your VPBX can be routed to VAPI, and you can also make outbound calls as needed.

thanks!

Vapi doesn’t use a separate extension field, you must configure your SIP provider or PBX to include the extension in the SIP URI, as Vapi routes calls based on the full SIP URI..

understood, thanks

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