Method of operating an interface device as well as interface device and exchange with such an interface device

Interface Device (IWF), for interfacing between a synchronous time-division multiplex access (ISDN) subnetwork and a statistical multiplex (ATM) subnetwork, comprising:

• a controller (SC) for connection by an ISDN signaling channel of a primary access connection to the ISDN subnetwork and by an ATM signaling channel of a user network interface (UNI) to the ATM subnetwork wherein the primary access connection has a fixed transmission capacity;
• and
• one or more devices (DI1, DA1;
• DI2, DA2) for connection to the ISDN subnetwork by one or more corresponding information links (C1, C2) comprising basic transmission channels (Ch1, . . . , Ch6;
• Ch20, . . . , Ch30) of said primary access connection wherein each information link has a required transmission capacity for connection to the ATM subnetwork by one or more corresponding information channels (VPC12, VPC13) of said UNI for converting information exchanged between the ISDN subnetwork in fixedly assigned time slots and the ATM subnetwork in the information channels under the control of the controller (SC) wherein the information channels occupy capacities corresponding to respective required transmission capacities of the information links such that only the respective required capacities are occupied in both the ATM subnetwork and the ISDN subnetwork.

An exchange (ISDN, ATM) including an interface device (IWF) for connecting a first telecommunications subnetwork (ISDN), operated in a synchronous time-division multiplex mode (ISDN) with a fixed assignment of time slots to transmission channels using a first signalling protocol, to a second telecommunications subnetwork (ATM), operated in a statistical multiplex mode (ATM) with a transmission capacity assigned to each connection using a second signalling protocol, the interface including:

• a controller (SC) for connection by an ISDN signalling channel of a primary access connection to the first telecommunications subnetwork and by an ATM signalling channel to the second telecommunications subnetwork wherein the primary access connection has a fixed transmission capacity;
• and
• one or more devices (DI1, DA1;
• DI2, DA2) for connection to the first telecommunications subnetwork (ISDN) by one or more corresponding information links (C1, C2) comprising basic transmission channels of said primary access connection wherein each information link has a required transmission capacity for connection to the second telecommunications subnetwork (ATM) by one or more corresponding information channels (VPC12, VPC13), said devices under the control of the controller (SC) for converting information exchanged between the first telecommunications subnetwork in fixedly assigned time slots and the second telecommunications subnetwork in the information channels wherein the information channels occupy capacities corresponding to respective required transmission capacities of the information links such that only the respective required capacities are occupied in both the first telecommunications subnetwork and the second telecommunications subnetwork.