S

service provider

A dynamic-link library that supports communications over a telephone network through a set of exported service functions. The service provider responds to telephony requests, sent to it by the TAPI dynamic-link library, by carrying out the low-level tasks necessary to communicate over the telephone network. In this way, the service provider, in conjunction with TAPI, shields applications from the service- and technology-dependent details of the telephone network communication.

subaddressing

A capability provided on ISDN lines that allows more information than just a single telephone number to be used when dialing.

Supplementary Telephony

Level of service that provides advanced switch features such as hold, transfer, and so on. All supplementary services are optional; that is, the service provider is not required to support them. See also Assisted Telephony, Basic Telephony, Extended Telephony.

Switched 56

A switched data service that lets the user dial someone else and transmit at full duplex, digital synchronous 56 Kbps for the price of a phone call.

synchronous

Data transmission method in which there is constant time between successive bits, characters, or events. The timing is achieved by the sharing of a single clock. Each end of the transmission synchronizes itself with the use of clocks and information sent along with the transmitted data. Characters are spaced by time, not by start and stop bits. See also asynchronous.