I've been clicking around the Flash-enabled VoIP eLearning Tutorial.
Authoritative, vividly illustrated, and totally cool.
You click, and you see illustrated guides to how VoIP works, how to configure VoIP, product configurations, features, and here's the killer app:
A Flash-enabled guide to the feature sets of more than a dozen popular VoIP phones. No Cisco, (maybe they didn't want to play ball) but Avaya, Comdial, Mitel, NEC, Nortel, Polycom, ShorTel, Siemens and others.
Funny thing, though,gang.. can't figure out who does this site. No "About Us" link. Went to the root address and got a screen saying the domain was "parked." Hope that doesn't mean this tutorial resource is going away. You never know. So, as Janis sang, "get it while you can."
Go there, come back here, and TalkBack about what you think.