It's been released for at least a week, but I finally took the time out to install the new 0.9.0 release of the VOCP Voicemail System -- and it's no joke, I've been waiting two decades for this.
Forget your Delrina bitmaster-pro whatever, VOCP lets us assign arbitrary structures of mailboxes, commands, faxbacks, announcements and scripts, interfaces with the Festival voice synth to read us our emails, it has a slick Perl/Tk control panel, a web-based read/download interface and lets us manage voicemail over the handset. It also handles caller-id, faxes, sends email notifications (optionally with the message attached), comes with a handy-dandy voicemail system-structure editor and command-line testing tools, and it has docs and an active mailing list. What's more, as if it needed more, unlike the aging Hylafax, VOCP actually works with modems still on the market ;)
Oh, did I mention it's GPL? The pet project of Pat Deegan at PsychoGenic.
ahhhhh ... open source perfection....