SIP Introduction

Create an Assistant

We’ll create an assistant with POST /assistant endpoint. This is no different than creating an assistant for other transports.

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{
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	"name": "My SIP Assistant",
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	"firstMessage": "Hello {{first_name}}, you've reached me over SIP."
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}

Create a SIP Phone Number

We’ll create a SIP phone number with POST /phone-number endpoint.

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{
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	"provider": "vapi",
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	"sipUri": "sip:your_unique_user_name@sip.vapi.ai",
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	"assistantId": "your_assistant_id"
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}

sipUri is the SIP URI of the phone number. It must be in the format sip:username@sip.vapi.ai. You are free to choose any username you like.

Start a SIP call

You can use any SIP softphone to test the Assistant. Examples include Zoiper or Linphone.

You just need to dial sip:your_unique_user_name@sip.vapi.ai and the Assistant will answer your call.

There is no authentication or SIP registration required.

Send SIP Headers to Fill Template Variables

To fill your template variables, you can send custom SIP headers.

For example, to fill the first_name variable, you can send a SIP header x-first_name: John.

The header name is case insensitive. So, X-First_Name, x-first_name, and X-FIRST_NAME are all the same.

Use a Custom Assistant For Each Call

You can use a custom assistant for SIP calls same as phone calls.

Set the assistantId to null and the serverUrl to the URL of your server which will respond to the assistant-request.

PATCH /phone-number/:id

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{
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	"assistantId": null,
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	"serverUrl": "https://your_server_url"
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}

Now, every time you make a call to this phone number, the server will receive a assistant-request event.