4 ports per card. Supports KX-T7700 (APT) series telephones Single Line (SLT) and DSS console KX-T0151 and KX-T0155 Cell Stations and Voice Mail. Maximum one per system. Please refer tKX-TDA50G System Capacities Chart #1 prior tconfiguring a system. This card will alsprovide XDP on all ports. This card will NOT support 90-volt message waiting lamps on single line sets.