Clear-Com V12PDDXY - Manual (Page 187)

Remote panel Any intelligent intercom device connected to the back-panel ports
of the system frame (matrix). This term does not refer to devices
connected through interfaces.
Sidetone The sound of the panel operator’s voice, as heard in their own
earphone(s) as they speak.
Source In this guide, the term source refers to a device (such as an
intercom panel, interface, or beltpack) that sends audio into the
matrix. The device to which audio is sent is called a destination.
VOX In the Eclipse / Eclipse HX system, when audio at a panel exceeds
a threshold, a light switches on at the panel’s port card to visually
cue the operator. The threshold level is set in the ECS / EHX
configuration software.
187 V-Series Panels User Guide