This point is more or less an extension of the point above. If you want to avoid sounding awkward and long-winded, you need to know what you're going to say — every good sales voicemail is conducted with confidence and definitive intention. The key to delivering on both is having well-prepared, personalized voicemail messaging at your disposal.
This ensures understanding and helps the prospect write it down accurately. However, don’t repeat yourself—say the same thing in a different way.

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.
I find it helpful to imagine that I am writing a memo when I leave voicemail messages. Outlining points enhances my own clarity and puts the listener on notice for the information.