A modular block for connecting, disconnecting and testing a telephone line, including a plurality of conductor holders each for connecting, or for disconnecting an insulated subscriber wire pair, a plurality of removable elements for providing a connection to an insulated subscriber wire pair, and for manually establishing or cutting the connection between a subscriber wire pair and a conductor holder, at least five, or a plurality of five connecting units each including one of the conductor holders for connecting a subscriber wire pair to a removable element in groups of at least five or a grouping of a plurality of five units, to form the modular block, the connecting units being arranged in two inversely symmetrical parallel rows to form one row and another row, with three of each five units being disposed in one row and the remaining two of each five units being disposed in the other row.