A multimedia data network (MMN) operating according to a packet switched standard and a circuit switched network (TABX) are connected without a gateway (GW). The circuit switched network (PABX) comprises a multimedia controller (MMC) which receives signaling messages from multimedia terminals (MT) and controls the switching resources (SW) of the circuit switched network (PABX) on the basis of these signaling messages during a call set-up. The multimedia controller (MMC) makes the multimedia terminals (MT) normal extensions of the extension space of the circuit switched network (PABX). Therefore, multimedia terminals (MT) and normal telephony terminals (TT) can perform a data exchange through the switching resources (SW) controlled by the multimedia controller. Additionally, the multimedia controller (MMC) can provide supplementary services of the circuit switched network to the multimedia terminal (MT). It is also possible that the multimedia controller (MMC) performs a network resource management of resources in the multimedia data network (MMN). Thus, the multimedia controller (MMC) provides a full integration of the multimedia terminals (MT) into the circuit switched network without using the functionality of protocol conversion of a gateway (GW).