SAN

Storage Area Network
 - A special network designed to interconnect multiple storage devices at high speed. Fibre Channel is often used.

S Bus

Device used to connect data terminals such as video conferencing units to ISDN lines.

SDH

Synchronous Digital Hierarchy - 
A synchronous transmission system used for telecommunications worldwide, operating up to many Gbit/s.

Serial Port

Port in a PC used for the connection of external equipment such as an external modem. Also used for connection of call-logging, CTI, etc.

Server

A computer, or software package, that provides a specific kind of service to client software running on other computers. The term can refer to a particular piece of software or to the machine on which the software is running. A single server machine can have several different server software packages running on it, thus providing many different services to clients on the network.

SHDS

Short Haul Data Service

Single-Fibre Cable

A plastic-coated fibre surrounded by an extruded layer of plastic encased in a synthetic strengthening material, and enclosed in a plastic sheath.

SiNET

Simple Integrated Network
 - A fully managed hosted IP telephony service.

SIP

Session Initiation Protocol
 - An Internet Engineering Task Force (IETF) standard, SIP is an open, Internet genuine protocol for establishing and maintaining multi-party, mixed media sessions over converged networks. SIP enables the creation and deployment of feature rich services that go far beyond simple VoIP calls.

SLA

Service Level Agreement
 - A contract between a network service provider and a customer that specifies, usually in measurable terms, what services the network service provider will furnish. Many Internet service providers (ISP)s provide their customers with an SLA. More recently, IS departments in major enterprises have adopted the idea of writing a service level agreement so that services for their customers (users in other departments within the enterprise) can be measured, justified, and perhaps compared with those of outsourcing network providers.

SLT

Single Line Telephone

SMDR

Station Message Detail Recording

SMDS

Switched Multi-Megabit Data Service