VoIP telephony known problems

When we offer VoIP-based services, we are careful to check that the internet connection to the building is capable of supporting the proposed services. Unfortunately, other providers are not so careful, resulting in unsatisfactory performance of VoIP-based telephone service, with any or all of the following problems becoming all too apparent.

Poor speech quality


The speech from the person you are speaking to sounds broken up with periods of silence. The silent periods can last from a fraction of a second to many seconds and make the conversation difficult or impossible to understand.

It might be the case that you can hear the other person perfectly well but they tell you they are having difficulty hearing you, or possibly the other way around.

The problem might be worse when you use your computer; for example, you look at a web site to find some information while talking to the other person.

If you have more than one IP telephone, the problem might be worse when 2 or more telephones are in use; the more phones in use at any one time, the worse the problem gets.


Your internet connection speed is too low for VoIP to work properly

Because speech is a real-time service, it is easily affected by low broadband speed. Most broadband services are 'asymmetrical', which means that the upload and download speeds are not the same. Typically the download speed is faster then the upload speed. As a telephone call is 2 way, it requires enough speed in both directions. Having a good download speed is not a guarantee of VoIP working properly; the upload speed must be sufficient as well.

There is a problem with your internet connection

Your internet connection might be fast enough to support VoIP but have a problem or fault that is not immediately apparent but that interferes with speech. You might have also noticed web pages downloading more slowly than they used to do.

There is a problem with your computer network

There are any number of possible problems with an office computer network that will interfere with the proper functioning of VoIP-based telecoms.

You share the office and broadband with other business in the same building

If you share an office building with other businesses and the landlord provides the internet connection, it will likely be shared with the other businesses. It might be the case that the internet connection is not of sufficient capacity to support all the businesses in the building and this shows up as poor speech quality on your IP telephone service.


Internet connection speed

Check your internet connection speed with one of the many speed test web sites, such as https://speedtest.net/. If the speed in either direction is below about 1Mb/s, that might be the cause of the problem. If the speed checker also shows a 'ping' time, anything over about 20ms can cause problems as well.

If the cause is a slow internet connection, the solution is either a faster connection or to have a separate internet connection used only for speech. Please contact us for advice.

Computer network problems

If you suspect there are problems with your computer network, please contact us for advice.

Shared offices

If you are using a shared internet connection and this is the cause of your problems, the answer is probably to have a separate connection just for use by your VoIP services and not shared with any other occupants in the offices.

Unreliable service


The service is unreliable, sometimes it works as expected, sometimes you can make outgoing calls but incoming calls don't ring your telephones. Sometimes callers, when they do speak to you, complain that they have tried several times but although they heard ring tone, your telephones never rang. Sometimes your telephone numbers seems to be out of service, even though everything is working properly in your office as far as you know.


Some routers have a feature called SIP ALG. Although this was intended originally to fix problems with internet-based telephony, it actually makes them worse, causing any or all of the above symptoms.


Usually SIP ALG can be disabled in the router. If you don't know how to do this, please contact us for advice.