Rishonly,
Three locations are connected to each other by one circuit.
Picture again wwwdotcom's triangle. A, B, and C are the corners of the triangle. These are the connections: A is connected to B along the AB leg of the triangle, A is connected to C along the AC leg, B is connected to A along BA, and to C along BC, C is connected to A along CA and to B along CB.
It is only one circuit with three phones on the circuit.
Does that answer your question?