What is a dedicated CO circuit that links two points called?

A dedicated CO (Central Office) circuit that links two points is referred to as a tie line. This type of circuit is specifically designed to establish a dedicated connection between two locations, often used for communication between two central offices or between a central office and a remote location.

The key aspect of a tie line is that it is usually dedicated for specific purposes, such as carrying voice or data traffic consistently between the points it connects. Tie lines facilitate direct communication and do not rely on shared resources or paths that could be impacted by varying traffic.

In contrast, other terms may describe different types of circuits or connections. For instance, trunk lines typically refer to higher-capacity pathways that connect multiple local exchanges or serve as a backbone between major switches but do not imply the same dedicated nature as tie lines. Connections line and P2P (point-to-point) lines may also represent connections but are not as specifically defined for this purpose as tie lines are in telecommunication contexts.