This isn't quite what you're looking for - but the Vokis (voki.com) will 
let you record by phone.
It's a fun "Talking avatar" type thing. You put in your phone number, 
and the website calls you!  you say your message and the avatar speaks 
it.     Students can send their vokis to you via email, or you can have 
them embed them in a blog or wiki.   There is a comment button where you 
can have a voki comment on the original one.

Not the "system" you describe, but the students would have a lot of fun 
doing it!  =)

Marlene  (all about fun)

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