Two-wire circuits are typically used in residential applications, so they should be fine for home offices. Offices with different types of data endpoints, such as telephones and modems, can use cross-connect wires. These may have either two-wire or four-wire circuits.ext to wire to connect to the public telephone system, there is wire to connect telephones and other endpoints such as modems and fax machines to the distribution system (likely a punch down block) via wall jacks.