The Red Phone

The Red Phone

The Red Phone is a SIP soft phone application for iOS and Android that you can use with an Asterisk VOIP server.

The Red Phone on iOS and Android

The Red Phone is built using the Linphone open source code, with only a few modifications:

  • It is painted red to match the colour scheme of our Raspberry Pi
  • It only has phone functions; the video and chat features in the Linphone core are hidden.
  • You can setup a ‘Red Phone Number’ to get one button dialing and auto answer from your most important contact.

The Red Phone on Google Play.  google_play_logo

User Guide

To connect to your Asterisk server, tap the settings button. You will need to know your user name and password,  and the IP address of the Asterisk server.  Your user name is usually your extension number on the Asterisk server. The IP address of the server will vary according to your setup; your server could be on your LAN, or accessible to the internet.

Screen Shot 2015-12-17 at 9.22.43 PM
iOS Settings. In this example, we are connecting to an Asterisk server on our LAN.
Android Settings – Tap Account Setup Assistant to create a new account. In this example, we are connecting to our Asterisk server on the internet.
The Android version supports multiple accounts simultaneously. We have it configured to connect to one Asterisk server on our LAN and another at

If you wish to enable the ‘Red Phone’ feature, enter a phone number in the settings.

Screen Shot 2015-12-18 at 5.04.33 AM  redphoneSettings

The Red Phone will automatically answer calls from this number. You can dial this number with one click of the phone iconchat_over.

Once you are connected to your Asterisk server, you can start making and receiving calls.


When you are in a call tap the Options button for additional features.  You can transfer a call to another number, or add numbers to create a conference call.

Screen Shot 2015-12-13 at 10.20.31 PM  Screen Shot 2015-12-13 at 10.21.10 PM


Setup Your Own Telephone Network

We use The Red Phone with our Asterisk VOIP server running on a Raspberry Pi to get free home phone service. The setup is described here:



License and Source Code:

The Linphone open source code is licensed under GPL. Linphone source code is available on GitHub.

Our modifications to the source code to build The Red Phone are available on Bitbucket.