Vertical Communications and FXT - Manual (Page 105)

Abbreviation Feature Definition
VAB
Voice Announce
Block
Inhibits your station from receiving a SOHVA. Also,
blocks voice calls sent over the speaker. When chosen
as a feature, stores a button that provides the function.
*Available only on Impact SCS 8412FJ and 8412SJ models only.
Large Screen Display Speakerphone Station User’s Guide 97
GCA70-349 Display Abbreviations