In comparison to an analogue connection, an ISDN subscriber line offers a whole range of advantages. The basic ISDN line allows multiple phones or communication devices, with different numbers (MSNs), to operate and use two parallel connections simultaneously. In addition, the ISDN connection also offers higher data transfer rates to an analogue connection using a modem, for example, when accessing the Internet.
To utilise the ISDN line, end users need special ISDN-capable phones or faxes. The use of so-called A/B converters, linking analogue devices to a digital connection, is common. Meanwhile, other techniques such as DSL or cable connections are used for connecting to the internet. Nowadays, phone technology is evolving away from ISDN and towards IP telephony via Voice over IP (VoIP).