I'm was in the call forwarding feature on my blackberry 7100i and under forward unanswred calls it gives 3 options: If busy, If No Answer, and If Unreachable. It gives the option of putting a fwding number in one or all 3. What is the difference between each one???

No Answer - If you let your phone ring but don't pick up.
Unreachable - If you're out of service area or have you phone off and the network can't reach your phone.
Busy - I could only guess if you have two active lines open like a conference call.

Does call fwd disable vmail? I want the call to be fwd instead of my vmail picking up.

I believe it does disable voice mail. It does on mine.

I would just try it and see?

call forwarding will not send to vm. that is default forward to no in all cases -