What is the difference between a modem, ISDN and DSL?
A modem converts your computers data packets into an analogue signal (sounds a bit like a fax machine) and uses the normal telephone network to pass this to your ISP (Internet Service Provider) who then turns the signal back into data and thus enabling your computer to communicate on the Internet. ISDN also uses the telephone network to transmit data to the ISP but does not convert the data to analogue signals; instead it uses digital equipment at the exchange and on your computer. DSL uses digital signals and your telephone line but at the telephone exchange your line connects to different equipment rather than the telephone network. This removes the limitation on speed that was being caused by the telephone equipment being used for data transfer when it was designed for voice samples and also removes the need for call charges from the telephone network. This means that DSL can offer fast always on connections at a cheap price.
