ADSL / DSL broadband enables your computer modem to share a voice telephone line, by transmitting data at high frequencies outside of the range of human hearing, thus enabling both computer and voice services to be used at the same time. Without any equipment installed between your broadband modem and telephone, the interference from the modem makes the telephone unusable as you can hear the high pitched squeal in the background. You also have to bear in mind, that unlike a standard 56K dial-up modem, a broadband modem connects to the internet as soon as you switch on your computer - as a result, the interference is noticeable as soon as you switch on the PC, even if you have not connected to your ISP (Internet Service Provider).
PhoneLine Splitter
Most broadband internet service providers send you a pack with modem and two DSL line filters to plug into the telephone sockets. However, this is often insufficient and the quality of the filters supplied often leaves something to be desired. You need to plug an ADSL/DSL line filter into every phone socket into which you need to plug equipment other than a broadband modem you then plug that equipment into the filter. Your broadband modem can be connected into any of these filters at the same time.
