Pre-recording answering machine

Some answering machines/voice mail systems allow you to press a button to listen to and possibly re-record the message you just dictated rather then deliver it, for example if you tripped over your words or just left out some info. How about a device on the caller side: you place a call and get a regular old answering machine, press a button, your phone hangs up immediately, then lets you dictate a message which you can proof-listen and alter until you get it just right, then you hang up, the device re-places the call and delivers the finalized message by itself. The device should be able to detect if it doesn't get the answering machine on the second call (like, if the party you are calling walks in the door in-between your calls) and alert you, rather than playing back your message.