Then, you will require a filter to connect your phone/answering machine.
Remember, filter divides your line for the use of different equipment and you will require a filter for each equipment you like to add.
However, you need not buy a filter as your ISP will supply it when you sign up for a package.
To find out the best broadband package, the following page can be helpful:
http://www.broadbandsuppliers.co.uk/compare.php