Nupoint 4.0 vs Exchange 2007/2010 for voicemail

[cknipe]

I'm trying to figure out what the upsides and downsides are to choosing Exchange 2010 over nupoint 4.0 as a messaging system. Im looking at deploying one of these into an 8-10 site setup with about 75-100 users at each site.

If you are using exchange for your voicemail, let me know where you think it may fall short in comparison to Nupoint.

Is there any resilient/redundant opotions in exchange, and how ofter do you need to renew licenses on this box? Do you just purchase them one time?

Thanks