The availability of broadband and it's speed is dependent on the level of 'noise' on your line. You may not hear this noise when you make a telephone call, but it can have a detrimental effect on a digital service like broadband.
The further you are from your exchange, the 'noisier' your line is likely to be. Noise can also come from interference from electrical equipment within your premises or even from the building next door.
So what does this mean in practice?
If you live a long way from a broadband-enabled exchange, there is a chance that the connection speed may not meet your expectations.
The good news is that this isn't an issue with fibre. So see if you can go faster now.