"U interface." YourDictionary, n.d. Web. 17 August 2018. <http://www.yourdictionary.com/u-interface>.
U interface. (n.d.). Retrieved August 17th, 2018, from http://www.yourdictionary.com/u-interface
The interface used to connect a pair of wires from the telephone company to network terminator 1 (NT1), which in the U.S. is typically part of the terminal adapter. The "Um interface," meaning "U-mobile," is the air interface in the GSM system. See ISDN terminal adapter. See also U.