> ## Documentation Index
> Fetch the complete documentation index at: https://plivo.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Build an App That Makes Phone Calls from Raspberry Pi

> Build a Raspberry Pi app that makes voice calls using Plivo's API

This project was contributed by Andy Fundinger, a professional Python developer and trainer. Andy built this integration as a way to teach his students how to make calls to their mothers on Mother's Day, using Plivo and a keypad attached to a Raspberry Pi.

<Frame>
  <img src="https://mintcdn.com/plivo/7-odxN9fJG_Dg1dt/images/raspberry-pi_image.png?fit=max&auto=format&n=7-odxN9fJG_Dg1dt&q=85&s=22bd526039a76c3e5012171e03730c81" alt="" width="1000" height="603" data-path="images/raspberry-pi_image.png" />
</Frame>

[Raspberry Pi](https://www.raspberrypi.org/documentation/faqs/) is a single-board computer that comes with

* A Linux-based operating system
* 700 MHz ARM11 CPU
* 256MB (or 512MB) RAM
* SD card storage
* 2 USB ports
* Composite and HDMI video out
* Stereo audio out
* 8 GPIO pins
* Wired Ethernet

## Build a Raspberry Pi call button

#### 1. RasPi Circuit Diagram and inputs flow via GPIO

I hooked up a four-button keypad to four of the Raspberry Pi GPIO pins as inputs,  then run a continuous loop to check whether the buttons have been pushed.

Circuit diagram #1

<Frame>
  <img src="https://mintcdn.com/plivo/EvRfP72Bjs4tuRt5/images/circuit_bb.png?fit=max&auto=format&n=EvRfP72Bjs4tuRt5&q=85&s=7608c12795f891e2ce6b56453b41a67a" alt="" width="1755" height="1521" data-path="images/circuit_bb.png" />
</Frame>

Circuit diagram #2

<Frame>
  <img src="https://mintcdn.com/plivo/EvRfP72Bjs4tuRt5/images/circuit_schem.png?fit=max&auto=format&n=EvRfP72Bjs4tuRt5&q=85&s=900dac20a5e1ccfaab9962d51e8ffae0" alt="" width="1908" height="1680" data-path="images/circuit_schem.png" />
</Frame>

#### 2. Call flow via Plivo Voice API

Plivo normally expects that you’ll be using it for a web app, so I had to fake that somewhat. Rather than building a full web app, I had each student create a single page that had at least the minimum viable XML to dial a specified number in response to the call being answered. We also played with having a little more in that XML file. But basically we told Plivo that it was a web service and Plivo was OK with that.

```py theme={null}
params = {
'from': "14245550100",
'to': '12015550164',
'answer_url':"https://example.com/static/call_mom/answerThenCallMom.xml",
'answer_method': "GET"
}
p.make_call(params)
```

Then you execute a script that makes an HTTP GET request for “answerThenCallMom.xml", which could be as simple as:

```xml theme={null}
<Response>
    <Dial>
        <Number>14245550100</Number>
    </Dial>
</Response>
```

Get the code for [my Raspberry Pi project on GitHub](https://github.com/Ciemaar/RaspberryPython-CallMom).

Contributed by Andy Fundinger