IOS 7 firmware not compatible, but downloaded all different kinds of ipsw?

Earlier today my phone said activation required. I went on itunes and it said my software has expired. My brother told me that I need to download an ipsw and then go into itunes and hold shift and click on check for update then and select the ipsw file. Only I have downloaded the ipsw for iOS 6.1.3 or whatever to try and restore it back to that and have tried the ipsw for iOS 7 and none of them have worked. They all keep saying firmware not compatible. I have tried downloading them for the iPhone 4, iPhone 4 GSM and the CDMA and still none of them are working. I'm ready to just restore this phone because it's driving me up the wall. I have tried different sites and different ipsws and it's just not working.

If you have anything less then a 4, it won't upgrade your phone

I had the same problem and I found a fix… I was downloading the newest iOS 7.0.2 ipsw and trying to update to that and got the same message as you… If you have the beta like me you have to download the iOS 7.0 ipsw not the 7.0.2… That worked for me and didn't lose any of my data then iTunes found the newest 7.0.2 on its own like it should
hope this helps you

Whatever you do, do NOT erase your phone. It doesn't help at all. The exact same thing happened to me last night, and i erased mine and (somehow) it's worse.