Converts the two-wire U-Interface that comes from the telephone company to a four-wired S/T-Interface to provide ISDN telephones, terminal adapters, and video conferencing systems access to BRI ISDN services. This unit conforms to industry standard 2B1Q line code for the U-Interface; ANSI T1.601, 1992, T1.605, 1991; ITU/CCITT I.430 standards; and is a FCC, UL, DOC, and CUL approved device. Its reliable design protects against lightening and power surges. Alpha Telecom Single Line NT1 w/ Switching Power Supply, 555-620A0