Connecting 4-Wire

When referring to intercoms, a four-wire circuit describes an intercom connection (I/O) where there are four wires (two paths) and the paths are different for talk and listen.

Analog or four-wire circuits use two pairs for balanced line-level audio signals, one for input and the other for output, using four wires in total.

Note: A four-wire audio circuit is further defined by the attribute that the two paths can be used for unassociated signals. This means that the source input is not always associated with or routed to the destination output. This is commonly known as a four-wire split or split port. At the time of writing, a split port is only available on Eclipse-HX Digital Matrix products.
Note: To minimize noise and meet regulatory requirements, use screened (shielded) cable when connecting 4-wire ports.