IPhone Wi-Fi with T-Mobile SIM card?

I previously used a Nokia and I have T-Mobile. I didn't have texting or internet. If I use the SIM card on my iPhone and use Wi-Fi, will I get charged at all? I know it's a silly question but when I used my iPhone months ago, the bill we got was higher than usual.

No, if you use your home's Wi-Fi you won't get charged by T-Mobile.

Well, yes and no. All carriers require a data plan for a smartphone so yea, if you use your iPhone on t-mobile you will get charged for it, but Wi-Fi does not count against data plan usage limits.