Can I use my iPhone before signing up with the phone company?

I recently got an iPhone from my Uncle. I want to use it to take pictures at my prom, but I haven't registered it with the new phone company.

Before this, I was using Verizon. Now I'm switching over to AT&T but I haven't actually signed up with them yet.

I'm wondering if I can register my iPhone (give it a name, put music on it) without signing up with the phone company first. If I upload music, will it still be there when I register it with AT&T? Same with photos? Could I still actually use the device for every function besides a phone before I register it with my number and AT&T?

If it helps, it's a 4s.

Yes. Right now it's basically an iPod. Photos and music will cling to and hand around in phone and on iTunes. Best luck.

You can use the iPhone for anything except cell calls and cell access to the Internet. So you can do anything that doesn't require the Internet, and you can use the Internet if you are in a wi-fi hotspot. But you can't send texts (except to other iPhones over wi-fi), and you can't make regular voice calls. You can certainly take all the photos you want, and you can send them to yourself or others via wi-fi or in other ways.