Hi,
Are you simply coverging voice and data (VoIP), ie. normally removing wide area voice circuits and piping voice over the data circuits or going the whole IP telephony route, ie. IP telephones on desks?
If it's IP Telephony, you have a lot of planning to do!
Firstly, I suggest developing a testbed of say a dozen phones around your campus, with a single Call Manager (later on in the development you may well wish to add levels of redundancy to your Call Manager back end) to keep things simple.
I cant say this enough. Plan plan plan!! Numbering schemes, might seem a long way off at the start, but as soon as you need them you'll be so happy you thought about it in the first place.
So get your small IP Telephony network talking to each other, making calls over your data network. Shouldn't take too long, but it's one hurdle at a time.
Then you'll want to move onto getting your VoIP network talking to your legacy PBX. You'll need to know what signalling your existing phones use, and something like a 30 way channel to hook your router up to. Create the gateway and start routing calls between your IP Phones and your IDX.
To get direct external voice calls, again you'll need something like an ISDN30 to your router (it doesn't have to touch your PBX), there are also Internet based companies who will forward your IP calls to the PSTN from your Internet connection if you wanted to go that route.
So at some time in the future, you've got a dozen phones, that can talk to your legacy IDX system phones and the outside world. You've worked out which features you need on your IP phones, which you don't and which you can't. You're happy with the technology - and probably employed a couple of administrators to look after the call manager(s).
Time for a group trial - a subset of your user base, to trial a larger scale implementation. How long? You decide. After the trial period, back to the drawing board with all you've learned so far, and do it again.
At this point - you might just be ready to think about migrating your user base to IP telephony.
A whole world of luck to you my friend. You're going to be busy!!
PS: Where is your University? There are several resellers who offer excellent training and consultant resource for these types of installations. I can't mention on this forum the guys I have worked with for many years now.
If everything is coming your way then you're in the wrong lane.