Abstract: Upgrading of a subscriber connection to another requires an upgrading work done by an electrician. According to the invention, the type of connection is upgraded by remote control. A switch matrix bus including several parallel lines (1-8) is placed in the access node. Connected fixedly in advance to the bus are interface units of an ADSL connection and, when desired, of an ISDN connection, however, in such a way that only one interface is connected actively to one bus line at a time. A controlled switch element (SE1, SE2) connects a line coming from a test relay (R3) located between the end of the subscriber line (e.g. SL3) and its interface to the switch matrix bus instead of the test bus. With a remote control signal supplied through network management a choice is made of which test relay connects the connected subscriber line to the controlled switch element.