OPTIONAL 3-SLOT BASE CARD (OPB3)
Uses a regular card slot.
This card is equipped with 3 connectors to receive the following option cards:
4 Channel Message Card (MSG4)
4 Port Doorphone Card (DPH4)
4 Channel Voice Message Card (ESVM)
4 Port External Input/Output Card (EIO4)
16 Port Echo Cancellation Card (ECHO16)
2 OPB3s can be used with the KX-NCP500 and 3 with KX-NCP1000.