I got it working so that the incoming message starts recording just as the outgoing message finishes.
So the mailbox sort of works. I'm pretty excited. Frankly I'm not sure what I should do next.
Some of the possible candidates:
-expose some sort of GUI functionality for playing received messages and/or alerting the user to the fact that messages were received. Seems like this would go on the "call list" tab on the SIP-communicator GUI.
-enable a time or size maximum on incoming messages. As it stands if the caller forgets to hang up it's possible that the incoming message might fill up the hard drive, which would be bad.
-Right now the incoming message is audio-only. Perhaps I could auto-detect if there is an incoming video stream and record to video if that is the case
-Set up custom outgoing messages, IE associate each outgoing message file with a contact so that if your mom calls she hears message A but if your boss calls he hears message B.
-Perhaps have a "record outgoing message" function from within SIP-Communicator? IDK if this is necessary as all the OSes SC comes on have some sort of sound recorder built in.
At first glance it seems as though a size cap on incoming messages is most important, followed by some sort of GUI exposure. But I'll probably put it to Emil and whoever else and see what rises to the top.