CISCO1601

one Ethernet, one serial, one WAN interface card slot

CISCO1602

one Ethernet, one serial with integrated 56-kbps DSU/CSU, one WAN interface card slot

CISCO1603

one Ethernet, one ISDN Basic Rate Interface (BRI) (S/T interface), one WAN interface card slot

CISCO1604

one Ethernet, one ISDN BRI with integrated NT1 (U interface), one S-bus port for ISDN phones, one WAN interface card slot

CISCO1605

two Ethernet ports, one WAN interface card slot