These might be linked together via the use of telephone lines, fiber-optic cables, microwave technology. Voice mail allows you to record a telephone message for someone to receive at a later time. Some Voice Mail facilities also allow the person leaving the message to review, edit or cancel the voice message. This creates a faster, clearer signal transmission that is useful for multimedia applications. ISDN is currently expensive to lease however should be becoming less expensive more accessible to the public as the technology moves forward.
Data communications is used in many applications of business and in everyday life.
Providing access to satellite television for entertainment . Allowing automatic interface of electronic data. Providing access to Internet and the World Wide Web.