Default [Q] Bricked my AT&T S4, put sim card in old iPhone 4s?

I have been having issues with "wifi unstable" on my AT&T Galaxy S4 for weeks now. I've tried everything I could find to fix it to no avail. I decided I'd give CM11 a try as a last resort before I buy an S5 or HTC One. Well I screwed up somewhere and now it says that AT&T has detected unathorized software... I will try to fix it when I get home and can download software etc.

In the mean time, can I pull the sim from my S4 and put it in my old iPhone 4s? Will that work or is that a bad idea?

Thanks!