yeh...i called sprint today. this is how you fix it. i have an htc evo. so here are the following settings you can do. first go to settings. then click on wireless networks. then click on moblie networks. there should be an option data roaming sound. uncheck that. then click on roaming and instead of automatic select sprint only.
i hope this helps...i jsut did it today...so far i havent heard any nose. yes it gets annoying. i started to notice it a while back but didnt do anything about it. but today i called up sprint and they helped me fix the problem.
anyways let me konw if it works or not...