[apristel]

You will stay on Sprint as long as it is strong. If you happen to switch to a different carriers tower you will stay on it throughout the call, even if the phone picks up a weak sprint signal. This way you won't drop a call because it switches you to a weak Sprint signal. Once you hangup you will then switch back to the Sprint tower after the call.

Basically it will give you a stronger signal. It helps.

Maybe Pokerpot can explain it better.