does jailbreaking cause network connection problems?

I kinda posted this kind of issue in the main iphone forum, and just wanted everyones knowledge. today i got my 3gs replacement from apple, which is a good thing by the way, my previous 3gs had problems with receiving a signal and unstable reception. the reception would go haywire when im outside and i would get "no service" inside. I was wondering if its because I jailbroke it and unlock it or it was just another hardware issue with my particular iphone