This group switching Ethernet module (10BaseT 48 port) provides 48 switched, 10-Mbps (10BaseT Category 3 unshielded twisted-pair [UTP]), half-duplex Ethernet ports using 4 telco RJ-21 connectors on the front panel (12 ports per connector). The telco connectors are numbered from left to right. The first segment of telco connector ports, starting on the left, are 1 through 12, the second segment of connector ports are 13 through 24, the third segment of connector ports are 25 through 36, and the fourth segment of connector ports are 37 through 48.