# Frequently used acronyms

Acronym | Description
AN | Access network. The portion of a public switched network that connects access nodes to individual subscribers. It is the last link in a network between the customer premises and the first point of connection to the network infrastructure, usually a point of presence (PoP) or central office (CO).
BCC | Bearer channel connection protocol. A protocol that allows the local exchange (LE) to instruct the access network (AN) to allocate bearer channels on demand, either singly or in multiple instances.
DLCP | Digital loop carrier protocols. Protocols that make use of digital techniques to bring a wide variety of services to users through twisted-pair copper phone lines.
DS1 | Digital Signal 1. A serial digital signal transmission format in which 24 duplex voice circuits are time division multiplexed into one 1.544 Mbps T1 digital circuit. Also referred to as T1.
EOC | Embedded operations channel. A channel provided on telecommunications facilities to support remote management operations such as provisioning, maintenance, protection switching, and alarm surveillance.
ETSI | European Telecommunications Standards Institute.
IDT | Integrated digital terminal. A virtual network element that represents the operation of a protocol (for example GR303) within a switch.
ISDN | Integrated services digital network. A standard for providing voice and data telephone service with all-digital transmission and message-based signaling.
HDLC | High-level data link control. A link layer protocol for point-to-point and multiple-port communications.
LAPD | Link access procedures for the D-channel. A protocol for communication at the data link layer.
LAPV5 | Link access procedures for the V5.2 protocol. A sub-layer of the V5.2 link layer that provides reliable, end-to-end communication paths between the AN and LE for exchanging PSTN signaling information and other V5.2 control information.
LDS | Local digital switch.
LE | Local exchange. Exchange in which subscriber lines terminate, having access to other exchanges, to national trunk networks, and to the central office (CO). A local exchange carrier (LEC) is a common carrier that operates local exchanges in a given geographical area.
PSTN | Public switched telephone network. The domestic telecommunications network commonly accessed by ordinary telephones, PBX trunks, and data communications facilities.
RDT | Remote digital terminal. The digital loop carrier multiplexer at the end of the digital loop carrier that is closest to the network interface. According to the GR303 protocol, an RDT provides the side of the interface devoted to subscribers. When communicating with the PSTN, a media gateway performs functions of the RDT.
TMC | Timeslot management channel. A channel used for timeslot allocation and de-allocation and for assigning and managing facilities connected to an LDS.