Assembly with functional module and method for connecting and building in such a functional module

The present invention provides an assembly for building into a prefabricated or prefab wall. The assembly comprises a mounting box (10) and at least one in the mounting box (10) mountable and via at least one cable (50) connectable functional module (21). The mounting box (10) furthermore comprises at least one tubular part (11) with a front end (13) and an open back end (14), and a closing part (12) that is attachable against the open back end (14) of the at least one tubular part (11). According to the invention, the at least one functional module (21) is connectable with the at least one cable (50) via the open back end (14) and is attachable in the mounting box (10) such that it is usable for an end user via the front end (13).