| Abbreviation | Definition |
|---|---|
| SGSN | Serving GPRS (General Packet Radio Service) Support Node |
| SGW | Server GateWay |
| SHD | Smart Handheld Device |
| SHDSL | Single-Pair High-speed Digital Subscriber Line |
| SHIT | Single-Hop Infrastructure Transmission |
| SHM | Short-Haul Modem |
| SHR | Self-Healing Ring |
| SIGTRAN | SIGnaling TRANsport |
| SIL | Speech Interference Level |
| SIM | Subscriber Identity Module |
| SIMT | Système interbancaire marocain de télécompensation |
| SINAD | SIgnal-to-(Noise And Distortion) ratio |
| SINAP | Signalling and Intelligent Network Applications Platform |
| SIO | Subscribers In Operation |
| SIP | Service Interface Point |
| SIP | Session Initiation Protocol |
| SIT | Special Information Tone |
| SITA | Société Internationale de Télécommunications Aéronautiques |
| SITA | Societe Internationale Telecommunications Aeronautiques |
| SITT | Spectrum Information Technologies and Telecommunications |