TABLE OF CONTENTS | AAL | ATM Adaptation Layer | |
| AARP | AppleTalk Address Resolution Protocol | |
| ABM | Asynchronous Balanced Mode | |
| ABR | Available Bit Rate | |
| AC | Alternating Current | |
| ACD | Automatic Call Distribution | |
| ACELP | Algebraic Code-Excited Linear Prediction | |
| ACF | Advanced Communication Function | |
| ACK | Acknowledgment | |
| ACM | Address Complete Message | |
| ACSE | Association Control Service Element | |
| ACTLU | Activate Logical Unit | |
| ACTPU | Activate Physical Unit | |
| ADCCP | Advanced Data Communications Control Procedures | |
| ADM | Add/Drop Multiplexer | |
| ADPCM | Adaptive Differential Pulse Code Modulation | |
| ADSL | Asymmetric Digital Subscriber Line | |
| AFI | Authority and Format Identifier | |
| AIN | Advanced Intelligent Network | |
| AIS | Alarm Indication Signal | |
| ALU | Arithmetic Logic Unit | |
| AM | Administrative Module (Lucent 5ESS) | |
| AM | Amplitude Modulation | |
| AMI | Alternate Mark Inversion | |
| AMP | Administrative Module Processor | |
| AMPS | Advanced Mobile Phone System | |
| ANI | Automatic Number Identification (SS7) | |
| ANSI | American National Standards Institute | |
| APD | Avalanche Photodiode | |
| API | Application Programming Interface | |
| APPC | Advanced Program-to-Program Communication |
| APPN | Advanced Peer-to-Peer Networking | |
| APS | Automatic Protection Switching | |
| ARE | All Routes Explorer (Source Route Bridging) | |
| ARM | Asynchronous Response Mode | |
| ARP | Address Resolution Protocol (IETF) | |
| ARPA | Advanced Research Projects Agency | |
| ARPANET | Advanced Research Projects Agency Network | |
| ARQ | Automatic Repeat Request | |
| ASCII | American Standard Code for Information Interchange | |
| ASI | Alternate Space Inversion | |
| ASIC | Application Specific Integrated Circuit | |
| ASIC | Application-Specific Integrated Circuit | |
| ASK | Amplitude Shift Keying | |
| ASN | Abstract Syntax Notation | |
| ASP | Application Service Provider | |
| AT&T |
