V.90 is the standard recommended by UIT-T, for the telephone Modem S being able to reach a speed of 56 kbit/s downstream and 33,6 kbit/s upstream. This standard was approved in September 1998, putting fine at the battle between 2 technologies of transfer 56 kbit/s, that is to say X2 of 3COM/U.S. Robotics and K56flex of Rockwell Semiconductor. This standard is also known under the name of V.Last because it was anticipated with being the last protocol for the telephone modems, its speed of transfer being very close to the theoretical limit to the phone lines standards (POTS). Finally it was improved under the standard V.92.