A modular telecommunications terminal block system includes one or more terminal blocks (10) which may be repeatedly installed and removed from a mounting rail (24). Each terminal block (10) employs a housing (12) having a telephone exchange wire carrier and a service wire carrier within the housing. An exchange to be connected to the terminal block (10) is inserted through an opening (36) in the housing and into the exchange wire carrier (20) which is movable between an open position and a closed position. By manually pressing the exchange wire (20) in the closed position, or by installating the terminal block (10) onto the mounting rail (24), the exchange wire is terminated to an exchange wire contact element (170) within the terminal block (10). A service wire is separately terminated within the terminal block and engages a service wire contact element (66, 68). Insertion of a linking module (16) into an access jack (120) provides connection between the exchange wire contact element (170) and the service wire contact element (66, 68).