T1

T1 in telecommunications refers to a high speed data line.  A T1 is actually a physical wire, or more precisely a cable, and can support a total data speed of about 1.5 Mbps (millions of bits per second).  T1 lines may be used to provide high speed internet service to some locations.  Another usage of T1 lines is for cellular base stations - to connect the cellular base station to the telephone central office for calls that will be routed through normal phone wire lines for part of their journey.

T1 lines are used in the US.  A similar wire data line used in Europe might be called an E1 line.