Actually it doesn't have anything to do with voice capabilities:
5-3-5. UNMONITORED NAVAIDs
a. All VOR, VORTAC, and ILS equipment in the NAS have automatic monitoring and shutdown features in the event of malfunction. Unmonitored, as used in this order, means that the personnel responsible for monitoring the facility have lost aural and visual ...
The chart supplement does list the magnetic variation of the VORs. Looking under the "radio aids to navigation" section for a nearby airport, it's listed at the end of the line, right after the elevation.
BATTLE GROUND (H) VORTACW 116.6 BTG Chan 113 N45º44.87´ W122º35.49´
160º 9.6 NM to fld. 253/21E.
Another source is the radio fix and holding data ...