Can I use iPhone without data plan?

My friend offered me to sell an iPhone to me but I have at&t phone service and data plans are so expensive. And I don't want to buy any data plans. Can I use iPhone without having any data plans or the at&t will know hat I'm using iPhone and they will start charging me.
Please answer my question As soon as possible.

Data roaming charges in Tenerife for an iPhone 4s?

I'm going on holiday to Tenerife tomorrow and deciding to take my iPhone 4s (my network is 3 mobile) not to make calls or texts or use the internet, but just to use the camera as it is really good. I don't pay my contract my mum does and she keeps on going that I better not rack up a huge bill whilst I'm out there. I know that the hotel I'm staying at has Wi-Fi so even if I do use the Wi-Fi will it be charging me and is there any thing I can do to stop myself from getting unexpected charges? I have turnt off data roaming but is there anything else I can do?

Do iPhones by Sprint work in Europe with another carrier s SIM card?

I have an iPhone 4s and I'm currently under contract with Sprint which uses CDMA technology, but it also lets you use GSM in Europe. I'm aware about the fact that you can use it with a Sprint's SIM card over in Europe, but the roaming charges are outrageous. What i would like to do is, once my Sprint contract expires and i go to Europe, I wanna be able to use another carrier's SIM card. Is that even possible?

Why does my iphone have no signal?

Iv'e had thhe iphone 3GS for 7 months and the singals always been fine. Today i lost signal and it won't come back, despite being in places that i know have signal.(such as my house) How can i get my signal back!

Can you use your iPhone as Prepaid?

I have recently acquired an iPhone 4 with a clean ESN and want to give it talk, text, and data capabilities without an annual contract or monthly fees. I have heard of the GoPhone program by AT&T and was wondering how to use it. I would be grateful for any information regarding this or any similar program.

Iphone 4s 5.1.1 jailbreak problem, no network?

I jailbroke my dads iphone 4s 5.1.1 last night, i downloaded iblacklist from cydia for my dad, he needed it, then this morning we noticed he wasn't getting any calls or texts, we tried to erase all content and setting, then it was taking way to long so we done a hard reset by holding power and home for 20 sec or so, then we had no signal at all, now i have just done a factory restore and cydia has gone which i'm assuming means its not jailbroken anymore, so we were still getting to network, i tried resetting network settings and still no network