IPhone getting charged for 3G use?

I just recently got an iPhone 4. I have a 2gig data plan. I use Wi-Fi whenever I can but if I don't have Wi-Fi and am therefore connected to 3G, I don't go on the Internet. However, Verizon has notified me that I have used 50% of my data package for this month. I thought using Wi-Fi made it so it DOESN'T go against my plan? Even though I don't use the Internet with the 3G, am I still getting charged for being connected to it?

Added (1). (With verizon)

Sound not working on IPhone 4S?

I had my iPhone for about a month and the sound was working fine. But now for some reason when I get a text it only vibrates. Not even th key board clicks r working! How do I fix this?

What should i ask if i'm buying an iphone from craigslist?

I want an Iphone 4s. I want to buy one from craigslist- maybe ebay- but i know i shouldnt just buy one. What are somethings i should ask them about before i buy one? Thanks! 12 points!

Added (1). Oh and i'm at&t so will the kind of service they used to use effect me buying it?

Will apple notice I replaced my iPhone screen?

Long story short, I cracked my screen and got it fixed at a repair shop. They somehow made my camera stop working (which they won't admit) but told me my phone is still under warranty and to take it to apple. The repair guy did his best to make it look like the phone has never been opened. (Voids warranty) I noticed the front camera (tiny cut out hole) looks a little less tinted when comparing it to other phones. You think they'll know if I'm lying? The camera is my favorite part of the iPhone.

Apple Mobile device won't install?

I have finally after 4months of trying downloaded itunes but if i plug my ipod or iphone 4s into my laptop to buy music and apps itunes won't sycnerise(sorry i don't no how to spell it) them and when i try to repair it it flashes up with a message saying " service apple mobile device failed to start." and they have buttons down the bottom saying ignore and retry and i have retried so many times and it still won't download mobile device. I have also uninstalled itunes but when ever i try to reinstall it either it doesn't reinstall or it just won't install apple mobile device and yes before you ask i do properly uninstall everything.

Is 300mb of data enough for the iPhone 5?

So, I can't figure out how much data usage I should get for the iPhone 5. At home I would always be connected to Wi-Fi, and when I'm out I'd just check FB, maybe Tumblr and my blog. I was going to go with At&T.
I've also read that people were going way over their limits and had no idea why, from just checking their FB their data usage skyrocketed. Has anyone else had that problem?
Is this just an AT&T problem or for all carries?

Why is all my iPhone GB used up?

I have a 8gb iPhone 4 and I'm about to upgrade to IOS 6, you need atleast 2.5gb free to update even though IOS 6 only takes up 599mb. When I go to my settings to see how much space i'm using, it says 6.8gb used yet I have deleted all my apps and all that, why is this? How can I fix it?