The first thing you need to do is have a talk with your supervisor about this! I wouldn't stand for someone lying about me like that. If you know who this person is who is doing this, then I would make sure that you tell the supervisor who did this, and have him talk to that person about these allegations. Make sure that you stand up for yourself without saying anything slanderous about the other person, as the boss would not look kindly on that. Hope this helps, good luck.
I have to wonder how you know about the voice mail. As a former manager, I would wonder about that. But, also, as a manager, I wouldn't give much credence to that type of information provided by voice mail. How well does your supervisor know you? Is he or she inclined to believe such rumors? I've been in your position, and fortunately my boss knew me better than to believe such nonsense. All those things considered, tiggersmom is right. You need to approach your supervisor and discuss the matter with her/him in a calm and collected manner. Good luck.
There is no defense against a lie
When somebody tells lies about you I think you should just leave it alone until it fades because if you know its not true you shouldn't let it bother you in any way possible.
Oh the nasty office politics! The way to repair the damage is to talk to your supervisor, find out what the situation is and be very calm. Do not in any way retaliate, or it will get back to the boss. Take the high road, and after ascertaining that your boss knows these accusations are just lies, be the best person and put it behind you. Pray for the person involved and be kind to that person in a normal way. Ignore her negative behavior and she may find someone else to pick on. Enough of this and the boss will figure out which way the wind is blowing. This is taken from personal experience.