SIP Trunking

Connecting Phone Numbers to Millis via SIP

Overview

Millis provides seamless integration for connecting your phone system to its AI-powered voice agents using SIP. This guide walks you through the process of rerouting phone calls to Millis via SIP.

​Step-by-Step Process

​1. Make a POST Request to /register_sip_call

To initiate a call, send a POST request to the /register_sip_call API endpoint. Depending on your location, select either the EU-West or US-West region for lower latency:

• EU-West: https://api-eu-west.millis.ai/register_sip_call

• US-West: https://api-west.millis.ai/register_sip_call

​Request Body

You must include the necessary parameters in your request body, with the option to customize agent behavior and include metadata if needed.

Request Body Example:

{
  "agent_id": "your_agent_id",
  "agent_config": {
    config options for the agent
  },
  "metadata": {
    "key": "value"
  },
  "include_metadata_in_prompt": true
}

Field Details:

• agent_id: (Optional) The ID of the Millis AI agent that will handle the call.

• agent_config: (Optional) Configuration options for the agent, allowing you to customize behavior.

  • If both agent_id and agent_config are provided, the parameters in agent_config will override the original parameters for the agent tied to agent_id.

  • You can also provide just agent_config for a temporary configuration, which will be used to construct an agent to handle the call.

• metadata: (Optional) Any additional information to attach to the session, giving the agent context to enhance its response. To learn more about how metadata works, visit the Metadata Guide.
• include_metadata_in_prompt: (Optional) Boolean value indicating if the metadata should be included in the agent’s conversational prompt.

​2. Receive the SIP URI

After making the POST request, you will receive a response containing a call_id and a sip_uri. This sip_uri is the address you will use to route your phone calls to Millis.

Response Example:

{
  "call_id": "unique_call_id",
  "sip": "sip:call-uniqueid@<millis-sip-server>"
}

​3. Reroute Your Call

Use the provided sip_uri to reroute the call from your phone system to Millis. Your phone system will forward the call audio to Millis, where the voice agent can interact with the caller.