Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line. The user's computer or router uses an attached modem to encode and decode information into and from audio frequency signals, respectively. Despite the proliferation of high-speed Internet access (broadband), dial-up Internet access may be used where other forms are not available or the cost is too high, such as in some rural or remote areas.