I ordered a brand new iPhone 5 from Amazon?

So I had ordered a brand new iPhone 5 from Amazon and i have the iphone 4 but will there be any fees since I don't have an upgrade in the near future to get a new phone? Will I have to pay a lot to switch the phones?

No. Back in 2009 I had a lg neon on AT&T, and I didn't like the phone so I bought a blackberry on eBay and AT&T didn't find out that I changed the phone.