This project demonstrates how to create a voice bot that uses Dailys PSTN capabilities to make calls to phone numbers, and if the bot hits a voicemail system, to have the bot also leave a message.

How it works

The server file receives a curl request with the phone number to dial out to
The server creates a Daily room with SIP capabilities
The server starts the bot process with the room details
When the bot has joined, it starts the dial-out process and rings the number provided in the curl request
When the phone is answered, the bot detects for certain key phrases
If the bot detects those key phrases, it leaves a messages and then ends the call
If the bot detects there's a human on the phone, it behaves like a regular bot

Prerequisites

A Daily account with an API key, and a phone number purchased through Daily
A US phone number to ring
dial-out must be enabled on your domain. Find out more by reading this document and filling in the form
Google API key for the bot's intelligence
Cartesia API key for text-to-speech

Setup

Create a virtual environment and install dependencies

python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate
pip install -r requirements.txt

Set up environment variables

Copy the example file and fill in your API keys:

cp .env.example .env
# Edit .env with your API keys

Buy a phone number

Instructions on how to do that can be found at this docs link:

Request dial-out enablement

For compliance reasons, to enable dial-out for your Daily account, you must request enablement via the form. You can find out more about dial-out, and the form at the link here:

Running the Server

Start the webhook server:

python server.py

Testing

With server.py running, send the following curl command from your terminal:

curl -X POST "http://127.0.0.1:7860/start" \
  -H "Content-Type: application/json" \
  -d '{
    "dialout_settings": {
      "phone_number": "+12345678910"
    }
  }'

The server should make a room. The bot will join the room and then ring the number provided. Answer the call to speak with the bot.

You can pretend to be a voicemail machine by saying something like "Please leave a message after the beep... beeeeep".
You should observe the bot detects the voicemail machine and leaves a message before terminating the call
You can also say something like "Hello?", and the bot will notice you're likely a human and begin having a conversation with you

Customizing the Bot

You can customize the bot's behavior by modifying the system prompt in bot.py.

Multiple SIP Endpoints

For PSTN calls, you only need one SIP endpoint.

Daily dial-out configuration

The bot configures the Daily rooms with dial-out capabilities using these settings. Note: You also need dial-out to be enabled on the domain, as mentioned earlier on in the README.

properties = DailyRoomProperties(
        sip=sip_params,
        enable_dialout=True,  # Needed for outbound calls if you expand the bot
        enable_chat=False,  # No need for chat in a voice bot
        start_video_off=True,  # Voice only
)

Troubleshooting

I get an error about dial-out not being enabled

Check that your room has enable_dialout=True set
Check that your meeting token is an owner token (The bot does this for you automatically)
Check that you have purchased a phone number to ring from
Check that the phone number you are trying to ring is correct, and is a US or Canadian number.

The bot doesn't detect my voicemail

The bot should be smart enough to detect variations of certain patterns,
If your voicemail machine doesn't follow the example patterns, add the pattern to the LLM prompt

Call connects but no bot is heard

Ensure your Daily API key is correct and has SIP capabilities
Verify that the Cartesia API key and voice ID are correct

Bot starts but disconnects immediately

Check the Daily logs for any error messages
Ensure your server has stable internet connectivity