PBXs generally prefer Ground Start . Loop start shorts tip to ring through a resistance. Single line phones prefer Loop Start . Ground start shorts tip to ground through a maximum of 550 ohms of resistance. Right behind the ball was a ring, insulated from the ball on one side and the shaft on the other.
Tip is the wire that goes to the tip, Ring is the wire that goes to the ring.
QOS is largely mythical at this time. CO, Central Office - The telephone company switching equipment to which your telephone system is wired by the Local Loop . Demarc - Demarcation point between the telephone company's equipment and your equipment. Today, the demarc is as close to the edge of your facility as possible. You are responsible for all wiring and equipment on your side of the demarc.