Polycom SpectraLink 6100 MCU : The SpectraLink 6100 MCU is conveniently sized to support 16 Wireless Telephone users and four Base Stations. Four SpectraLink 6100 MCUs can be connected together by an Inter-Processor Communication (IPC) cable to support as many as 64 users and 16 Base Stations.The SpectraLink 6100 MCU is connected to the telephone switch or Centrex lines by an RJ-21 connector and is powered by 24-volt DC through a 120-volt AC adaptor. An administration mode allows you to easily add or remove Wireless Telephones from the system, make changes to the MCU configuration, and download software updates if necessary. LED lights on the front panel indicate the status of lines and Base Stations. The SpectraLink 6100 MCU can be easily mounted in a standard 19-inch equipment rack with the purchase of a separate rack mounting kit.