In the US you would use the standard IP Office with cards/modules designed for Nortel phones. Most Norstar phones (including 7310 and 7316e) are supported and work quite well. You can also have Avaya phones on the same system - connected to cards/mods that support those phones. Norstar IP phones are also supported - but are rumored to not work so well.
IP Office is a different animal as compared to MICS/CICS. Steep learning curve. To be authorized on the product formal education is required. A demo/lab system and using all of your spare time rattling around in it is also a good investment.
Good luck. Mike