Delay Ring - Is COS timer based I believe, but I can't remember the correct variable at the moment. I always think of it as your phone would start to ring on the 3rd and 4th rings of the person who primarily answers that line.
Ring Cont - If the user is on a line already, instead of single-ring alerting the user that another line has an incoming call, it will continuously ring.
Delay Ring Cont - Combination of the about two