Why does my 20Mbps broadband have an actual speed of 7Mbps?


We regularly get queries about broadband speeds and why they do not appear to be as fast the advertised speeds.

Currently ADSL2+ broadband is offered over standard telephone lines with connection speeds advertised as being “up to 20Mbps”.

However, no-one that has a broadband service that is advertised at “up to 2oMbps” can actually achieve a speed of 20Mbps.

[NB Mbps stands for Megabits per second and is technically the bandwidth of the internet connection, but it is commonly referred to as the speed of the internet connection.]

Actual speeds

Connection speeds on ADSL broadband services that are advertised as being “up to 20Mbps” typically vary from 1Mbps to 18Mbps depending on the length and quality of the telephone line used to transmit the broadband signal from the customer’s premises to the telephone exchange.

Unfortunately, there nothing that can be done about these speed variations as this is the nature of ADSL broadband provision over standard telephone lines.

The longer the telephone line and the poorer the line quality then the slower the broadband connection speed.

The same applies to fibre-to-the-cabinet (FTTC) services such as BT Infinity.

The relevant distance with FTTC services is not the distance to the Exchange, instead it is the distance to the nearest street cabinet where the copper from your premises and the fibre to the exchange meet.

Beyond the master socket

Its not just the telephone line outside your house or business premises that can affect your broadband connection speed.

In fact in our experience most slow speed problems and differences in speed are caused by faulty wiring or equipment on the other side of the master socket in the end-user’s premises.

To ensure that you are experiencing the fastest possible speed on your telephone line you should first ensure that your internal wiring is up to standard and that any connected telephone equipment is not causing interference.

You must also ensure that your filters are working properly and that a filter is connected to each socket.

You should then compare your speed with neighbours who are on the same service by checking your speed at various times during the day using the BT Wholesale speed test service.

You may wish to contact Premitel and take advantage of our telephone engineer call-out service to ensure that your internal wiring and equipment is satisfactory.

Unfair pricing?

All internet service providers have a single price for their advertised “up to 20Mbps” service.

In other words, customers that have a 1Mbps service are charged at the same price as customers that are lucky enough to achieve speeds of 15Mbps.

This would seem to be unfair, but from the point of view of the internet service provider the cost of providing service to low-speed customers is the same as that for providing service to high-speed customers.

It could be argued that it is not the fault of the internet service provider that the customer lives a long way from the exchange.

By-passing the local exchange

Some remote communities have found a way of increasing their broadband speeds by reducing the length of their telephone line.

They have achieved this by installing the broadband equipment in their local telephone line distribution cabinet rather than in their local telephone exchange.

This is similar in concept to what BT Openreach are doing with their Fibre-To-The-Cabinet (FTTC) service (see below).

This solution offers broadband service where previously none was possible and also significantly higher speeds to those who previously had a very slow broadband connection.

However, this is an expensive solution since the community has to pay for the equipment that is installed in the distribution cabinet together with the connection from the cabinet to the internet.

The other way to bypass the local exchange to achieve higher broadband speeds is to use a wireless connection of some description (eg community WiFi, satellite or mobile network).

Fibre to the Cabinet

In the last few years Fibre To The Cabinet (FTTC) services have attempted to minimise the problems caused by speed degradation caused by long telephone lines. This is achieved through the installation of high speed fibre from the exchange and terminating it in the telephone cabinets nearer to customer premises.

This has two advantages. One is that there is a higher starting speed available from fibre. The other is that the speed degradation is less because the length of the telephone line has been shortened.

In other words the length of the telephone line has been reduced from the distance between the exchange and the customer premises to the distance between the cabinet and the customer premises.

Other broadband speed issues

Another problem with broadband speeds is that the speed that the telephone line supports is usually not the actual speed that is experienced.

In other words the broadband connection to the local exchange is synchronised at (say) 10Mbps, but the actual speeds indicated using a speed-test service are much lower.

The reasons for this are associated with general internet congestion and congestion on specific websites.

For example, if you access a USA website at 10.00 GMT it is likely to offer a faster service than if you accessed the same site at 16.00 GMT. Similarly, if the website that you are trying to access is popular at the time you try to access it (eg HMRC website on 31st January) then the speeds experienced will be slower than at other times.

Get in touch with Premitel if you have a specific requirement or if you wish to discuss how your business could make better and more cost-effective use of its existing telecommunications and internet infrastructure and services.