i cant quite seem to reliably toggle it on or off
What is a voice tag?
The one in the HUD or the one above players’ heads?
IIRC there was no way of removing the one in the HUD, and allowing that would make it possible for server owners to spy on players’ microphone and record their voice without them knowing.
Not true, you can define a new derma control with the title “VoiceNotify” and it will overwrite the old one. In this case make a blank panel.
oh, that’s reassuring
To disable the ones in the right hand corner you overwrite them as solid_jake said. The one above the players you have to set the material to a blank material, at least this was how it used to be done.