Abstract: A connecting block for electrically connecting a plug of a telephone set to a telephone line includes a base plate having a terminal for connection to the telephone line, a jack unit including a jack having an opening for inserting the plug thereinto, the jack unit having parallel side walls across the jack opening, a pair of parallel retaining members extending upwardly from side edges of the base plate for removably retaining the jack unit therebetween, and a cover for enclosing the retaining members, the jack unit and the terminal, the cover having a window to which the jack opening may be exposed. The arrangement of the jack unit and the retaining members is such that the jack opening may selectively extend parallel to the base plate or perpendicular thereto.