Refer to the exhibit.

What is the difference between a PBX and a keysystem under the Device tab?

A.
A PBX is where each phone has nearly identical configuration whereas akeysystem has a
unique extension for each phone.

B.
A PBX is where each phone has a unique extension whereas akeysystem has nearly identical
configurations for each phone.

C.
Akeysystem can be activated only by the operator by turning the Systemkey. A PBX operates
24×7 and requires no activation.

D.
Incoming PSTN calls tokeysystem users have to be routed through an auto-attendant or an
operator. Incoming PSTN calls to PBX users can be answered by any user on any line.