Nope is the quick answer, whenever customers have professionally recorded greetings I upload from my laptop through a phone with a Head Phone to female Curly Cord adaptor I had made.
Not brilliant but better than the other option which would be to backup the system, search through the backup for a weirdly named Linux sound file, convert your sound file into the same format and name then restore the whole system.
^^^^^ That reads massively easier than it actually is!
