Help This phone using data all day and night?

[dongemus]

My sister just got this phone and it is using way too much data. She only gets the 200mb/mo plan and never used over 100 with her old HTC WP7 phone. She went on the TMobile website and it showed that there was heavy usage while she was sleeping... like 30megs some nights! Does anyone know what is causing this?

I have my phone on another network with unlimited data so I never had to deal with this. Do I need to root it? Does anyone know if there is some carrier bloatware that uses heavy data?

Thanks in advance.

 

[El Presidente]

Does she have autosync turned on? If she turned that off she might see a reduction.

She could also take a look at Network Traffic Stats to find out exactly what's eating her data.