this is assuming that you are going to put a CD player on your system for Music on hold.
to connect music on hold you will need to get a few things from radio shack.
1 telephone jack PN 279-0420 and 1 1/8 in to lug converter cable PN 420-2454 1 1/8 in stereo to mono adapter PN 274-0882 or 1 RCA in to lug converter cable PN 42-2449 1 RCA 1F2M sterio to mono adapter PN 55024227 If your CD player has a different connector than 1/8 inch or RCA then you will need a different adapter.
connect the lug jacks of the converter cable to the red and green screws of the phone jack. connect two pieces of wire from the red and green screws of the phone jack to the MOH pair on the block MICS:Yl/Or CICS:Vi/Gn 3X8 6X16 8X24:Vi/Sl (see FAQ's on wiring for pinout) Note the jack is only used as a point to connect the lugs to cross connect cable.
connect the jack end of the converter cable to the stereo/mono adapter