Phone calls do not count as "data" but do, obviously, count against the minutes on your plan. It is important to note that while connected to Wi-Fi, only MMS uses data. iMessage, Apps, mail, web browsing, etc, all utilize Wi-Fi over EDGE/3G/4G, while MMS does not, regardless of Wi-Fi connectivity.

Do phone calls use data?

Wireless companies provide mobile data so you can make and receive phone calls, send and receive text messages, stream videos, check social media and browse the web. However, making and receiving phone calls and sending and receiving text messages does not count against your mobile data.

Does your phone use data when your not on it?

You're using your mobile data whenever you're not connected to WiFi and doing things like browsing the web, checking social media, sending iMessages, and streaming videos. When it comes to how we use our phones, it's especially important to understand data usage.