Great question! Although I don’t know if there is a specific function for this on your particular phone, the best way to save the message is the simplest. Turn up the sound as high as you can and record it onto a digital recorder (like you would use for a lecture), a cassette recorder or your cell phone if you have a voice recorder on it. Then save it as an MP3 on to your computer for safe keeping. You can also Google your vtech model number to see if you can find an owner’s manual. They might have a way to save a recording in there. Probably not, but it’s worth a shot.
By default, the telephone number is the one assigned to you by your organization, but it could also be a cell phone number or email address. In that case, voice mail would be played back through your email Inbox.

6. I can’t come to the phone now because I have amnesia and I feel stupid talking to people I don’t remember. I’d appreciate it if you could help me out by leaving my name and telling me something about myself.
While a short recording may not seem like a place to win new business, the professionalism, courtesy, and clearness that you convey in your greeting will leave a favorable impression in a customer's mind.