1. A transmission path between end user terminal equipment and a switching center.
2. A channel between an end user’s network interface and local end office. [T1.506-1989] Synonym [loosely] loop.
3. A communications facility extending from a customer’s premises to a serving central office comprising a subscriber line and, if necessary, a trunk facility, e.g., a WATS access line, TWX access line. [47 CFR Pt.36-A]

An access line composed of digital facilities, containing no analog sections, and having a digital interface at the local digital exchange office (DEO) and a digital interface at the end-user voice terminal, voiceband data terminal, PBX, or interconnecting network. [T1.508-1998]

A user access line normally used for analog voice communication, but which has special conditioning for use as a digital transmission circuit.

An access line (e.g., for WATS or TWX service) between a subscriber’s premises in one toll rate center and a serving central office located in a different toll rate center. [47 CFR Pt.36-A]

In the Defense Switched Network, an access line specially conditioned, usually by providing amplitude and delay equalization, to give it characteristics suitable for handling special services, such as reducing data signaling rates (DSR) to a rate between 600 b/s and 2400 b/s.

A communication path between local exchange and a customer interface (CI). [T1.401-1988]