The project MUSA was carried out within the framework of the contract arranged with Portugal Telecom (1994-1996). The equipment developed consisted of the ATM Multiplexer (ATM interfaces of 2 Mbit/s and 34 Mbit/s) and interfaces for CBR circuit (2 Mbit/s) emulation. The unit can include up to 14 cards. The 34-Mbit/s boards have 1 port, the 2-Mbit/s ATM cards have 2 ports and the CBR board have 4 ports. The 400Mbit/s commutations are implemented at the bus level. Some units have been already developed and provided to PT.