Day 14 of the Anvil Advent Calendar

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Get a robot to call your Aunt

Today we have an app for those of you who can never quite find the time to call up your least-favourite Aunt and wish her ‘Merry Christmas’. Wouldn’t it be useful if there were an app for that? No? Well we’ve built one anyway.

Enter her number and a robot voice will wish her a Merry Christmas over the phone:

You can get a copy of the app’s source code here:

Open in Anvil

How it works

The Twilio API makes automating voice calls a breeze. You’ll need to start by registering with Twilio and setting up a phone number. It only took me a couple of minutes to do, then I stored the Client ID and Secret Key in my Anvil app using the Anvil Secrets Service.

Once that setup was done, it was the work of just a few more minutes to set up a UI for entering my Aunt’s phone number, a server function to place the call, and an HTTP API callback endpoint to script the call when it’s answered:

@anvil.server.callable
def make_call(to_number):
  
  # Load the Twilio-account-specific details from the Anvil Secrets Service. You will need to set these values to use the app yourself!
  account_sid = anvil.secrets.get_secret('twilio_account_sid')
  auth_token = anvil.secrets.get_secret('twilio_auth_token')
  from_number = anvil.secrets.get_secret('twilio_number')

  # Make a REST API request to place the voice call, passing a callback URL where Twilio will get its instructions when the call connects.
  anvil.http.request(
    f"https://api.twilio.com/2010-04-01/Accounts/{account_sid}/Calls.json",
    data={
      "Url": f"{anvil.server.get_api_origin()}/call-connected",
      "From": from_number,
      "To": to_number,
    },
    method="POST",
    username=account_sid,
    password=auth_token
  )

    
    
# This function provides the API callback endpoint where Twilio gets its instructions when an outgoing call connects.    
@anvil.server.http_endpoint("/call-connected")
def call_connected(**kwargs):
  return """
    <Response>
        <Say>Dear Auntie, I hope you have a very merry Christmas. Sorry I didn't have time to phone you myself. Lots of love, me.</Say>
    </Response>
  """

You can clone the app to adapt it yourself here:

Open in Anvil

I’m sure my Aunt would be delighted to get a call with my automated Christmas wishes, but your mileage may vary. Just don’t blame us if you receive particularly hideous socks next year.


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