Can you use a file for your outgoing message?

New to this topic so please be patient with me...

I've created an audio file that I would like to use as my outgoing message, but I'm not exactly sure if I can integrate it into my phone.

I have a RAZR v3m through Alltel.

I have Motorola PhoneTools and have successfully transferred ringtones to and from it, but this is my first foray into trying to use a file as the outgoing message.

I know how to access it through the menus so that I can speak into the microphone, but I'm trying to avoid that route. I don't want to play the file and hold the microphone up to a speaker. I wanted a "clean sounding" outgoing message.

So my question is: Is this a possibility, and if so, how does one go about doing it? Any and all help would be greatly appreciated.