Another way to track these - along with the various other forms of content I write for them - is to view my profile page on the site.
Aside from being published on a serialized basis, these three VoIP features are also part of a more comprehensive buyer's guide, with additional content prepared by another contributor that profiles the leading vendors. This has all been pulled together under the title "Choosing a VoIP Vendor", and has just been published on their portal.
For anyone just starting down the path with VoIP, I think this will be a valuable resource, but I'll let you be the judge. Comments are welcome as always, as is any form of sharing.