12.1 ACRONYMS AND DEFINITIONS
Some terms are defined at the locations referenced in the Index.
Indication that the following characters are a hexadecimal expression.
Class 5 Electronic Switching System, CO voice switch that serves end users.
Two signaling bits in T-1 CAS when using a superframe.
Four signaling bits in T-1 CAS when using the extended superframe.
Augmented Backus—Naur Form.
Area Code, in telephone number.
Automatic Call Distributor, PBX function or machine to spread calls among phones.
ACKnowledge, message type to confirm receipt of request or action taken.
Analog-to-Digital Converter, first step to encode voice as a digital stream.
IP address of a host; MAC, DLCI, or other L2 destination or source identifier; cf socket.
Adaptive Differential Pulse Code Modulation, form of compressed voice encoding.
Authentication Header, form of IPsec that digitally signs but doesn't encrypt.
Form of PCM companding used with E-1 links.
Application Level Framing.
Application Layer Gateway.
Automatic Location Information (Identifier), geographic indication associated with a telephone, landline or cellular, delivered to a PSAP with E911 call; kept in an ALI database.
Acknowledgment Number, associated with an octet in a TCP stream or a packet.
Can take on any value to represent sound; see digital.