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.
2.) A gracious phone message is 30-45 seconds when talking to those we don’t know well. As George Washington said (yep, that George Washington), and I’m paraphrasing, “With men of business, be brief.” Be pleasant, and get right to the point. You’ll appear more confident and capable of handling the situation which merited the call.

Good professional voicemail greeting examples. A business named Lorem Ipsum, which sells widgets, wants to leave a brief message that confirms for the listener that they have called the right business. The message would also prompt the caller to provide information needed to return the call, and throws in a nice quick promotional note.
If you like to keep things simple, opt for a basic greeting. Most voicemail options allow you to record just your name, which lets callers know they’ve reached the right person.