56k line
A 56k line is a cable or wire capable of transmitting information at the rate of 56,000 bits per second. The 56k modem technology is a solution for end users and SOHO (small office/home office). When originally introduced, two technologies emerged: X2, which was developed by UsRobotics, and KFlex, which was introduced by Lucent and Rockwell. Unfortunately, with competing standards this caused confusion and difficulties for end-users and the ISP (Internet service provider). For example, if an end-user had an X2 modem, but the ISP only had KFlex modems, the end-user would be unable to achieve the optimal performance.
Because of this dilemma, an ITU (International Telecommunication Union) V.90 standard was developed. This standard merged X2 and KFlex that allowed maximum performance and compatibility.