Hardware support for communication networks, ISDN: the I420 interface standard and associated chip support

An integrated services digital network (ISDN) is a telecomms network, or several overlaid networks providing a number of services. These services may include, for example, telephony, data or text transmission. Customer access to these services is via a common access point, the user/network interface. There are currently two versions of this interface specified-the basic rate and the primary rate interfaces. The paper is concerned with the basic rate interface which provides the user with two 64 kbit/s channels plus a 16 kbit/s signalling channel. The primary rate interface provides thirty 64 kbit/s channels and is intended for PABX access