What type of broadband connection do I need for the phone system?


We recommend a dedicated FTTC (Fibre to the Cabinet, or superfast broadband connection). This is  more to do with the stability of the connection rather than the amount of data bandwidth that is  required.

We offer a free software trial so that you can try it yourself and see what you think? As part of the trial  we will provide access to a timer that measures the round-trip time to our servers showing you whether  the speed of your connection will manage the demands of voice at all.


Our customers have found that running a system on an ADSL 2+ connection is fine most of the time.  But the electrical signal over the length of the copper cable sometimes leads to occasional dropped  packets. With Fibre to the Cabinet the electrical signal over copper has a very short run and is therefore  much more stable.

Shared Circuit

Voice uses very little space on a broadband circuit. So why not share? The reason why we recommend  dedicated broadband circuits is that occasionally with shared broadband circuits, during a large data  download, the data can bleed into the voice and interrupt call quality. There is nothing you can do about  this. Programmes are designed to use all available connectivity, so YouTube, Microsoft 365, Dropbox,  Google drive will use all the connection they can get. This will impact the voice data which may cause  poor call quality or dropped calls. So, most of the time your voice calls will be fine but perhaps not all of  the time.

This is the same with all providers because the data download swamps the router before any  management protocols can priortise the traffic. The only way around this is a managed shared circuit  which is more expensive than a dedicated voice circuit.

You could try and get away with it on small sites by diverting calls to voice mail or mobile where they  are avoiding the swamped circuit allowing you to maintain good call quality.

Dedicated Circuit

A dedicated fibre circuit is more stable as there is no interference from other programmes giving you  stable voice all of the time.

Poor broadband Connectivity

You can still use this system with poor or no broadband. You just use it to manage the inbound calls and  then forward the calls onto other telephone numbers.

Test your Connectivity here http://fast.uk.voxbit.net/

Interpreting the results

Normally the upload speed is slower, and therefore the limiting factor. The amount of data a voice uses  makes depends on the codec. Typically, a mobile call will use 30Kbs of data. Normally the system is set to  provide for a higher quality of call by using a codec that uses 100Kps.

So, if you achieve an upload speed of 434Kps then your circuit should be able to support upto 4  simultaneous calls.  If you adjust your codec to G729 (or similar), it could support 13 / 14 calls.

A 2Mbps would support 20 calls using a 100mbps connection.


This is a measure of the variability of the connection speed. If the Jitter score is above 10 then you should  expect some call quality issues.  If the score is above 20 then you should not use the circuit for voice calls.

Sometimes you might find that a wireless or mobile connection has reasonably fast speeds but the jitter  means that the call quality can be unsatisfactory.

Ping test

This is the round time journey for a packet of data. A Ping score of under 100 should mean voice will work  well.  A score of over 150 will lead to call quality issues.

It is worth running the test several times during the day and collating the results to tell you how the circuit is  working.