I am not (yet) familiar w/Nupoint but I know the day is likely coming. What we do presently with our Octel is run the thing on redundant message drives and not ever back it up. If you lose a drive get on the phone to the vendor.
The thinking here is that voice mail MESSAGE backups are a waste of time because they are all time-sensitive material and we (wisely, IMO) disallow permanent saves and huge mailboxes. All my users are restricted to 25 messages and 21 days. Voice mail should never be allowed to become a long term storage repository because you will have users who will abuse it, i.e., lawyers, who never delete anything.
We perform tape backups once a quarter (every 90 days) but only backup the user configs and greetings.
Intelligent deployment and use of voice mail can sure save you a lot of headaches down the road.
Once we get a new unified messaging system and the user can then have his voice mails as .wav files on his computer, he can have as many as he wants and do whatever he wants with them because it will no longer be my responsibility to hold his hand if something happens.