Hello VAPI team, We currently use Issabel as our PBX and a physical gateway with Movistar SIM cards, where Issabel connects to the gateway via a SIP trunk to convert VoIP calls to GSM. Traditionally, for outbound calls, an agent answers through a softphone. However, we now want customers to interact directly with VAPI during the call (for example, to listen to real-time voice messages or navigate through automated menus). Given this outbound call scenario, my questions are: What is the best way to integrate VAPI so that customers can interact directly with it during an outbound call? Do you recommend connecting VAPI via SIP to Issabel (as a SIP endpoint or via the dialplan) to intervene in the call, or is there a more direct integration option with the gateway? I am not sure if this is the correct approach to implement VAPI in this case, or where exactly VAPI should be positioned in this scenario. any info is helpfull. here are some specifications: - CNT SIP Trunk: This is a SIP connection provided by CNT. It is used to handle specific types of calls (such as fixed or international calls) or to serve as a backup route. In the current flow, it acts as an alternative depending on the configuration and route availability. - Gateway: This is a physical device that serves as a bridge between Issabel and the cellular network. It receives calls via a SIP trunk from Issabel and converts them into GSM calls, enabling connection to the mobile network. - Movistar SIM Chips: These are the SIM cards installed in the gateway. They allow the device to make calls using the Movistar network by converting VoIP calls into mobile calls to reach the customer’s cell phone. Note: I have reviewed the documentation regarding BYO and SIP for outbound calls, but I’m not entirely sure if this is the correct approach. The goal is to have VAPI replace human agents for outbound calls, allowing customers to interact directly with VAPI. Thank you!

Hi there! 👋 Based on your setup with Issabel PBX, physical gateway, and SIM cards, I've found some integration options for VAPI: ### Best Integration Approach The most effective approach would be to set up a SIP trunk on your Issabel PBX that points to VAPI's SIP endpoints. This allows VAPI to handle the customer interactions during outbound calls while leveraging your existing infrastructure [discord-doc45](https://discord.com/channels/1211482211119796234/1211483291191083018/1334251359519641692). ### Integration Options Option 1: Direct SIP Integration with Issabel

1. Configure a new SIP trunk in Issabel specifically for VAPI
2. Input VAPI's SIP hostname and credentials into the PBX
3. Set up your dial plan to route specific outbound calls through this trunk

This approach positions VAPI between Issabel and your gateway [discord-doc84](https://discord.com/channels/1211482211119796234/1211483291191083018/1334821142204121088). Option 2: Using Twilio as an Intermediate Layer If direct integration proves challenging, you could use Twilio as a SIP bridge between your system and VAPI. This can help with authentication methods that might not directly interface with VAPI [discord-doc15](https://discord.com/channels/1211482211119796234/1211483291191083018/1335340719317192714). ### SIP Configuration Example Here's a sample configuration snippet for setting up the SIP trunk:

json
{
  "provider": "byo-sip-trunk",
  "name": "YourPBXTrunk",
  "gateways": [
    {
      "ip": "YourPBXIPAddress",
      "port": "5060",
      "netmask": "32",
      "inboundEnabled": true,
      "outboundEnabled": true,
      "outboundProtocol": "udp"
    }
  ]
}

[discord-doc30](https://discord.com/channels/1211482211119796234/1211483291191083018/1340813822193041499) ### Important Considerations

but is it even possible to connct to issabel with vapi. and what should the sip configuration should have in order to work properly with Vapi and issabel

The approach is to set up a BYO (Bring Your Own) SIP trunk in VAPI that connects to your Issabel PBX. This allows your existing infrastructure to connect seamlessly with VAPI's conversational AI capabilities. Step 1: Create a BYO SIP Trunk in VAPI Step 2: Configure Issabel PBX On your Issabel PBX side, you'll need to: \- Create a new SIP trunk in Issabel that points to VAPI's SIP endpoints \- Configure your dialplan to route specific outbound calls through this trunk VAPI uses the SIP REFER method for call transfers. Ensure your Issabel PBX is configured to: Accept and process SIP REFER messages. For VAPI to interact with callers, ensure your configuration supports: Bidirectional audio streaming Sample rate of 16000 Hz (as VAPI expects this for optimal speech recognition) Refer to the following guides that demonstrate how to establish a connection with your SIP provider. Note: While these guides use Twilio as an example, the process remains consistent across other telephony providers.

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Let me know if you need any clarification on any part of this integration, or if you'd like more specific details about any aspect of the configuration.