Does GV use your mobile to mobile minutes when making a call to a mobile device... or will it use anytime minutes any time you use it?
Inbound calls are normal, if the call is from a mobile number, it's charged as a mobile, if its form a land line, its charged as a land line.
Outbound calls are another story. Since Google Voice calls an access number to place the call, and that number is a land line, Sprint charges you as if you were dialing a land line.
Sprint has an add-on that allows unlimited inbound and outbound calls to any three numbers. The add on is no longer technically offered, but with some complaining it can be added. it costs $5 per month.
i simply watched what outbound # Google voice was using to connect my calls and added that as one of my three numbers. There are however a couple of things to look out for.
-Google sometimes changes the access number that it dials to connect calls, keep an eye out for this
-If and when Google does change the number, Sprint will not allow your access numbers to be updated until the start of your next billing cycle. Meaning if your billing is on the first, and Google changes your number on the 10th, even if you call Sprint and update the number, the change will not take effect until the 1st of the next month.
I have been doing this since the first of the year with my Hero, and now my EVO and I am quite satisfied with the way that it is working out.