Some decent replies in here to get someone started. But I get a bit frustrated in that there is no comprehensive guide to setting up FreePBX with Office 365. Regardless if you see the option in the Commercial Admin module. Yes, it gets you closer to getting it to work, but you still have to beat FreePBX/Centos with a stick to get it to work.
I will post a "how to" in a moment. Stand by.