Not Picking up Wi-Fi Signal

When I first started using my iPhone, it picked up our houses wi-fi signal just fine, throughout the whole house, but now I am lucky if it picks it up at all. I thought maybe it was our wireless router, but it isn't. As I sit here on my laptop, the signal strength it is recieving is excellent (the highest), yet I am lucky if mny phone even picks up the signal. Whats more, when it does pick up the signal, and I have three curved bars above the icon, when I go to safari, it immediately switched back to the Edge network, so on the rare occasion I do get connected, it won't stay connected.

What's the deal?