Polycom RMX 1500 Administrator's Manual page 816

Chapter 20-RMX Hardware Monitoring
20-18
When using the Hardware Monitor to monitor units on MPM cards
installed in the RMX's slots, ISDN related DSPs are named smart,
indicating their additional MUX (Multiplexing) functionality.
System
Components
in MCU Slots
Units on
MPM Card
MPM Card