The acronym ISDN stands for Integrated Services Digital Network. This means that ISDN gives you the ability to integrate a wide variety of services such as speech, facsimile, video telephony, Internet access, data and image transfer on your existing telephone line. There are two kinds of ISDN access:

• Basic Rate Access (BRA) offers two 64kbit/s channels (known as B channels) and one 16kbit/s channel (known as the D channel). The two B channels can be used for speech, facsimile, video telephony, Internet access, data and image transfer by the user and the D channel is used for setting up the ISDN call and monitoring. The D-channel can also be used for packet switching services e.g. Credit card authorisation and Speed points.
• Primary Rate Access (PRA) offers 30 B channels of 64kbit/s each and one 64kbit/s D channel which is used for setting up the ISDN calls and monitoring.