value added network service (VANS)
Network services are divided into basic services and more extensive value-added services. These value-added services are referred to as Value Added Service(VAS), Value Added Data Service (VADS) or International Value Added Network Service (IVANS).
All of these value-added services build on the messagingprovided in the basic service over the communications link. Value-added services have an additional benefit for the user, which can be the storage or processing of the message transmission.
A well-known example from voice communications is voice storage; others include line monitoring, traffic flow management and the rapid provision of appropriate transmission capacity.