activation error message

my Iphone 4 is showing a activation error message and when i try to activate it using itunes all it will display is unable to continue with activation at this time. I am so lost right now. I have googled youtube and have had a few friends look at my phone and we are all lost with coming up with something that will allow me to use my phone again. I downloaded the latest version of iTunes. I've done everything I could think of and what I have found online. so please help me. the next thing to do is to go into att and have them look at it.