Nortel Modular ICS Key Service Unit. Provides 0 incoming lines and 32 telephone station ports. Provides 2 slots for incoming line (trunk) cartridges and 2 slots for expansion cartridges. Add 2 - T1 Trunk Cards or 2 - 4x0 LS/DS or CLID trunk cards for up to 48 incoming lines. Additional Details ------------------------------ Product description: Nortel Modular ICS Key Service Unit. Provides 0 incoming lines and 32 telephone station ports. Provides 2 slots for incoming line (trunk) cartridges and 2 slots for expansion cartridges. Add 2 - T1 Trunk Cards or 2 - 4x0 LS/DS or CLID trunk cards for up to 48 incoming lines.