The NEM-40A/ C is a 40 channel lamp memory master with handset and built in all call.

40-Call Master Lamp Memory System with Handset series is a selective calling open voice style intercom system.

Features:
40 Stations Console master system with Lamp Memory, where call-in signal remains until answered
VOX ( voice actuated) handset on master station for privacy
Expandable to 120 stations with the addition of 20 and 40 call add-on selectors
Selective calling, Group calling, or All Call Separate transmit, receive, All Call, and call tone volume controls
Push-to-talk or vox handset at master, hands free at sub station
Wall or desk mounted