demarcation point

meeting point for communications devices of two separate entities (ex: junction where home telephone equipment connects to the wires of the telephone company)

In telephony, the demarcation point is the point at which the telephone company network ends and connects with the wiring at the customer premises. A demarcation point is also referred to as the demarc, DMARC, MPOE, or minimum point of entry.
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That point at which operational control or ownership of communications facilities changes from one organizational entity to another. Note: The demarcation point is usually the interface point between customer-premises equipment and external network service provider equipment. Synonym network terminating interface .