How do I change the number of rings on my Sprint Katana before it goes into voicemail?

How do I change the number of rings on my Sprint Katana before it goes into voicemail? Right now it takes about 297 rings before it goes into voicemail and I want to cut it down to like 3 or 4. How do I do that?How do I change the number of rings on my Sprint Katana before it goes into voicemail?call sprint and talk to their technical care. they can change the call forwarding delay.. usually its been 10-30 secs before it goes to vm. so if you choose 10 secs, that would be equivelent to about 3 rings