VoIP for decent sized company??


In Runtime
Any medium sized company admins on here that work with VoIP?

Got a contract meeting tomorrow and the boss mentioned only today about the possibilty of putting VoIP into their offices. I reckon they will need a system to look after maybe 60/70 posts and possibly the same total of posts spread over the country.
If anyone could throw me some names so i can read up tonight/morn it would be mucho aprreciated.
I wouldn't be installing this myself at all, I just need to blag it, throw some names/specs etc at him then if it went further i'd contact the sales guys concerned of a few companies.
I would definately imagine we are not looking at Skype/Gizmo etc, but a hardware install with full proper support from a main name in the game (ooh lordy, that rhymes!) until the onsite admins learn and can support it.

Or am i babbling utter dross?

Thanks in advance guys and gals.