Data hogs

[Jlm24]

Can anyone tell me why the default dialer and messaging apps on my phone are using my data? I've started using onavo and it's showing me that together both of those have used over 100 mb over the past couple of days. I'm on the 2 gb plan and I generally plan to use all or most of it each month. I've taken steps to lessen my data usage by getting onavo and the opera mini browser, but I still want to know why those are using data when I pay separate charges for them.