01 numbers are not free from landlines, they up to 13p. They used to indicate a number was at national rate, the numbers just after indicating the location, known as the area code. These may be for home or business use.
Although these numbers are usually located in the UK or Northern Ireland they need not be as what are known as virtual telephone numbers or one that gives you a local telephone number despite living abroad can be created, paid for by monthly subscription. They may also be mobile numbers but they still remain the same price. The only exception is 01 numbers from Guernsey, Jersey and the Isle of Man which are subject to a higher price, they begin 01481, 01534 and 01624. You can buy an 01 number for any use on our website here.
The 01 prefix to British numbers began in 1995 and there are currently 581 different regions around the UK. When ringing from outside the UK you should start the number with +44 and drop the 0.
As well as many mobile phone lines introducing an 01 number many business landlines are changing from 01, preferring the free phone lines. It is becoming harder to work out whether a number is from a landline or mobile phone from the number itself.