|What MWCC says is correct if you live in the UK. Most DSL is provided through a BT telephone line and BT wont supply a telepone line without a telephone service unless you live in one of the areas where the local loop is unbundled and you have no need to go anywhere near BT. But those area are usually in the big cities where there are plenty of customers.|
However, once you have paid for line rental, the cost of calls is minimal, zero if you dont make any calls. It is the line rental that costs the money and you are going to have to pay that with or without a phone service.
However, ther is no technical reason why you can't have DSL and no phone service. It depends on the telcoms providers were you are.