mini telephone system intro

Can you put together a powerful versatile cost effective telephone system? Well the answer is definitely yes in view of the way both hard & software technology has recently evolved, yielding increased ratios of CPU power to the £ as well as becoming more accessible to the general public at large. But more importantly the power of the internet and the role it plays in the sharing of detailed documented successful implementation of the required off the shelf modular parts. The internet also serves as the display platform of choice for a numbers of open-source communications projects ,inclusive of full documentation & working software ready for free download. (Asterisk, FreePBX, Elastix, Xivo etc.)

Lets explore one of the many feature rich low cost solutions that can be built using a Raspberry Pi 3 single board micro computer and the praiseworthy incredible PBX telephone system software platform. Before we begin, irrespective of the level of success that can be achieved with this combination, be forewarned that it is imperative you take measures to ensure that your system is secure and that you take steps to minimise any potential financial losses.   

Items Required List

  • Incredible PBX download for the Raspberry Pi
  • Raspberry Pi 3
  • Micro SD Card
  • Raspberry Pi 3 Power Supply Unit
  • Raspberry Pi Case
  • HDMI Lead
  • Ethernet Cable
  • USB Mouse
  • USB Keyboard
  • Internet access
  • Local Area Network
  • Hardware IP Phone or Software IP Phone
  • VOIP Trunk

Anybody that currently runs or has considered running a small telephone system at home or in a business will be aware of the typical high cost, closed shop nature of a combined package and in some cases the limited access to system administration/configuration (fixed feature sets, locked feature sets, cost to add features, high total cost of ownership, fixed term contracts, telephone line rental lock in, maintenance contracts, engineers call out charges, configuration back up charges, configuration restore charges , replacement battery charges, the dilemma of buying second hand, etc...).

Given that for what ever reason you need a telephone system, what alternative choices do you have? DIY, historically this has been quite a difficult task in terms of access to suitable equipment and documentation. If you could obtain the right hardware, software & skill sets only then could you start the technical learning curve. However this is no longer the case in view of the many available & ready to use communications tool sets based around innovations such as Asterisk.

Incredible PBX
Incredible PBX is a secure and feature-rich implementation of the complex communications tool kit known as the Asterisk, this implementation has a strong PBX security model. Designed to be ready for use as a service out of the box, delivering a comprehensive collection of useful utilities. It is however like many technology based innovations very USA centric at initial installation but can be modified for UK requirements. Typically Asterisk based systems will run on a Linux platform/operating system, however once it is up & running it can be configured/administered via a standard browser window & remote terminal access such as SSH or Putty, effectively allowing you to use your preferred Operating System and browser. You can think of the Incredible PBX as an interpreter to the complex world of Asterisk or the graphical user interface that sits on top of Asterisk.

Raspberry Pi 3
The Raspberry Pi 3 made in Wales UK, as indicated in the name is a third generation design of a low energy consumption credit card size single board computer that can be up and running for less than £50 including power supply, SD card & case (other parts such as TV, USB keyboard and mouse if not already owned can be sourced locally or online for £30 - £40). Its was originally designed to help promote computer science in schools and developing countries. However it has clearly, since 2012 been able to deliver affordable functionality to a greater audience. The Raspberry Pi 3 has a very high performance to cost ratio and has a rapidly growing user base in  both the professional & hobbyist arena. It's popularity has earned it recognition from mainstream outlets such as Maplins, RS, CPC & Amazon as well as many specialist online suppliers such as MODMYPI.

Technical Specifications
A 1.2GHz 64-bit quad-core ARMv8 CPU
802.11n Wireless LAN
Bluetooth 4.1
Bluetooth Low Energy
4 USB ports
40 GPIO pins
Full HDMI port
Ethernet port
Combined 3.5mm audio jack and composite video
Camera interface (CSI)
Display interface (DSI)
Micro SD card slot
VideoCore IV 3D graphics core
85.60mm x 56mm x 21mm, with a little overlap for the SD card and connectors which project over the edges
weighs 45g

Micro SD Card

  • The minimum size of microSD card for use with the Raspberry Pi 3 should be 8GB
  • Not all Micro SD cards are equal, they are generally defined by class. Try to use a good quality class 10 card.
  • Buyer be warned about the steady trend in fake SD cards, try to buy your card from a reputable outlet.
  • Always shutdown your Raspberry Pi prior removing the power then inserting or removing your SD card.

The above guidelines are very general as such you may wish to understand a little bit more in order to obtain the best results for your telephone system project. Essentially its about read & write speeds. Here a a few links to help you on your journey of discovery:-


There are lots of places to buy SD cards from, if you are in a bit of a spot and need a good quality SD card right away you should consider your local camera shop. However if you are able to plan out your project in advance you could get the same or better quality card for roughly half what you will be charged at a local camera shop. You could start by giving a go.

Raspberry Pi 3 Power Supply Unit
Put simply not all power supplies that fit your Raspberry Pi 3 will do the right job. Essentially its about the current rating, as such its best to spend the £7 - £10 for the right unit with a rating of at least 2.5A (2500mA). That way its just one less potential problem in the equation to figure out in the event of any performance related issues. Why not buy one directly from the Raspberry Pi foundation to be on the safe side and support a good cause at the same time.

Raspberry Pi Case
Hundreds to choose from online, if you want something custom made why not contact a local 3D printer company. Alternatively see if your have a Hack space lab or FAB lab near by.

Any standard HDMI cable should be fine for the purposes of the initial set up of your telephone system, once the initial set has been performed you will be able to access all configuration and administration via a remote computer or tablet on the same network.

Ethernet Cable
A standard Cat 5e cable will be enough to achieve the wired connectivity you require, you may also like to explore the wireless capabilities of the Raspberry Pi 3 if your wireless network is secure enough for your needs.

USB Mouse & Keyboard
If you do not already have spears knocking around, look out for a basic keyboard & mouse combo kit. These are normally less than £10.

Internet access
Connect the Ethernet cable to your network access, directly to your router or via a switch.

Local Area Network
The local network created by your router / switch.

Hardware IP Phone or Software IP Phone
Lots of online deals to be had for a standard hardware IP phone, start with something simple and easy to configure. Alternatively you could always try one of the many free software based IP phones. This could be installed on the computer that you are using to remotely access your Raspberry Pi.

VOIP Trunk
Try and locate a free service for testing, but give serious consideration to opting for a paid service if you want to use it for business purposes. Here are some names to start you of in your search for a provider that will fit your needs.

  • vonage
  • sipgate
  • freespeech
  • draytel
  • VoIPtalk


If you are in the Greater Manchester area and need some help setting up your Pi telephone system then contact Peter at Burytec Telephone Engineer Manchester service.


Submitted byJUDY ROGERS (not verified) on Wed, 17/10/2018 - 07:01

This is good. Also, could you suggest anything about IP phone solutions?

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