Information on Integrated Services Digital Network
The Integrated Services Digital Network (ISDN) provides for the
integration of voice and data (as well as other formats
such as video and graphics images) over a digital transmission
network. GSM defines its own air interface, or radio interface.
other interfaces in GSM,e.g. base transceiver station (BTS) - base
station controller (BSC) and base station controller (BSC) - mobile
services switching center (MSC), are based on 64 Kbit /
s ISDN channels.