| Abbreviation | Definition |
|---|---|
| ATS | Automatic Transfer Switch |
| ATTL | Aishwarya Technologies and Telecom Ltd |
| ATTRA | Appropriate Technology Transfer for Rural Areas |
| ATU | African Telecommunications Union |
| ATU-C | ADSL (Asymmetric Digital Subscriber Line) Transceiver Unit - Central office end |
| ATU-R | ADSL (Asymmetric Digital Subscriber Line) Transceiver Unit - Remote terminal end |
| ATZ | Attention: Reset modem |
| AU | Audio Units |
| AuBW | AutoBot Walkthrough |
| AUSPI | Association of Unified Telecom Service Providers of India |
| AVD | Alternate Voice/Data |
| AVR | Automated Voice Response |
| AVT | Audio Visual Telecommunications |
| AWA | Advanced Wireless Access |
| AWCC | Afghan Wireless Communications Company |
| AWS | Advanced Wireless Services |
| AWT | Agence Wallonne des Télécommunications |
| AZDL | Adjusted Zonal Daily Load |
| B | Bits |
| B3G | Beyond Third Generation |