Sharing Phone Contacts

As of late, we have been using Gmail to share via active sync, our phone contacts.

The reasoning behind this was that we wouldn't have to create email contacts for everyone, or AD users, I guess. 

I have to admit though, it does work. 

I am trying to figure out a good way to utilize either Exchange 2010 or 2013 (we're licensed but not yet installed with the latter) to share these contacts in a meaningful way (through active sync), without having to purchase another software to do it.

We have over 100 phone numbers, and they change constantly. We have over 100 devices that see these contacts.