FormerlyHemlock
Hero
Next aspect, can I fake a different 'mental voice'?
Perhaps with the use of the Performance or Deception check? It should obviously be something that can be resisted with an 'Insight' check or similar.
If it were at my table--I'm a Julian May fan, so I'd say no. Your farspeaking voice has a unique mental signature. On the other hand, you can use it as an infallible method of authentication, so it's not all bad.