Protect your hardware investment with 3Com's grow-as-you-need and mix-and-match solution. Unlike traditional, fixed-port stackable servers, the RAS 1500 is a stackable base unit that accepts expansion units that provide slots for additional plug-in I/O cards or ISDN PRI T1 or E1 connectivity. This unit supports dial-in, shared ISP access, individual dial-out, and LAN-to-LAN applications.