Well, most telecom ones are modular, so you could go from having multiple POTS lines to using a T1 by adding or swapping a module. Voice mail is usually implemented the same way. As you can probably tell from my previous post, I'm a little biased against new entrants into the field, as I just don't trust them. On the other hand, I've had very little experience with them, and I could be totally wrong. Also, I think that VoIP is a bad idea, and it seems that most of these new entrants want to head in that direction. So there is some bias there.

However, I imagine that the admin UI for the new ones is probably about a thousand times easier to use than the UIs for any of the older systems. They're mostly still based on the idea that the tech would be controlling the whole thing from a touch-tone phone, and, as such, the commands are more oblique than any Unix system. (That is, for example, ``vi'' for an editing command is the height of clarity as compared to most PBXs' commands.) But again, I could be wrong about that. I know for a fact that Nortel has implemented a Windows UI over the top of their PBXs that translate and execute commands for you after you use a more obvious interface, but it's Windows only, and not inherently networkable, so you'd have to use PC Anywhere or VNC or something to make that work from your desk -- not that that's a horrible option.

I guess what I'm saying is that I'd look at real telecom equipment first, including used stuff (most dealers I've used will sell you both new and used), and, then, if the price is prohibitive, or the interface too obscure, then go with the new stuff.

However, if you do go with the new stuff, let me know how it works. I'd be interested in suggesting it if it's as solid as old stuff.