I looking for advice on upgrading an existing small office setup.
Here is what we got:
Partner ACS system w/ an ACS 509 R7 module and a 308EC module being fed by 6 POTs lines in a hunt group servicing 13 Partner 18D phones. We also have 3 direct FAX lines outside the Partner ACS and a T1 going into a Cisco 1700 for our server internet connection.

We are looking to upgrade to VOIP and upgrade to a 2x bonded T1.

My question is how does the VOIP solution connect into the Partner ACS?

Our carrier wants to sell us an Adtran 908 w/ a PRI handoff, will that work w/ the Partner?

What are the right questions to ask, is there a better solution?

Are there any drawbacks to going completely VOIP?

Any thoughts about the best way of going about this would be helpful.