<p>I mean with Asterisk I can use any sip provider, I can hook up normal ISDN (or whatever) telephone lines and even connect normal ISDN or VoIP telephones to it any way I want.</p><p>And of course, it can just send voicemail to e-mail... that's a trivial feature.</p><p><a href="http://www.theregister.co.uk/2013/06/07/office_365_unified_communications_video_review/">Keep reading...</a></p>