A communication device (1) is described, comprising a powered transceiver (2), a line transceiver (3), an isolation circuit (4) comprising three capacitors C.sub.b1, C.sub.b2 and C.sub.b3, which are coupled between the powered transceiver (2) and the line transceiver (3), and a control circuit (5) arranged for controlling the transport of power from the powered transceiver (2) to the line transceiver (3) and for accomplishing a bi-directional communication across the isolation circuit (4). The control circuit is a two-mode controlled circuit (5), arranged such that during a first mode said power is transported and a communication in one direction is performed, and that during the second mode the communication in the other direction is accomplished. Such a device (1) and circuit (4) is small, has low capacitor values, and can be used at high switching frequencies up to several hundred MHz in telephony, medical instruments, industrial processes, modems, control and/or measuring apparatus, telecommunication apparatus and the like.