To set up a home telephone line, you will need to pay for someone to connect it, maintain the line and send you a bill. This process is paid for by charging the customer line rental.
Most phone lines are provided by BT wholesale, who provide the phone line to the house from the exchange, and maintain the line up to that point.
Once the phone is in your house, it is then managed by a telephone retail company, a service BT also provide but one that you can get from a variety of different providers, depending on the area you live in.
BT wholesale open up some of their exchanges and allow other providers to pay them a fixed rent to use their phone lines.
Companies like Talk Talk, Sky, O2 and various others offer these services. You will receive a monthly bill from whichever company you choose, which will include your line rental, any call package you decide to take out, and other calls which aren’t included in that call package.
The company will then pay a chunk of that line rental fee back to the company who maintain and provide the line, which is usually BT wholesale.
Many people assume they must get their line rental from BT, as they maintain the majority of the nation’s phone lines, but this is incorrect and you can often save money by looking at other providers.