I can not activate the iPhone ios 7?

Okay. If you would like a little help, you might want to describe any error messages, etc.

Try this link for activation problems ...

http://support.apple.com/kb/ts3424

If you had iOS 7 BETA installed, just go to developer.apple.com and log in using your developer account. There are discussions about this issue. Otherwise... for non-developers, I'm afraid you're on your on. Use Google.