phone line

telephone connection, line that connects to a telephone service provider

A telephone line or telephone circuit (or just line or circuit within the industry) is a single-user circuit on a telephone communications system. Typically this refers to the physical wire or other signaling medium connecting the user's telephone apparatus to the telecommunications network, and usually also implies a single telephone number for billing purposes reserved for that user.
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Noun
1. a telephone connection
(synonym) telephone line, telephone circuit, subscriber line, line
(hypernym) connection, connexion, connector, connecter, connective
(hyponym) digital subscriber line, DSL