Activation server unavailable for iPhone 3GS

Hello Everyone!

I am trying to activate my iPhone 3GS, but while doing so it says...”Your iPhone could not be activating because the activation server is temporarily unavailable Try connecting your iPhone to iTunes to activate it, or try again in a couple of minutes. If this problem persists, contact Apple Support at apple.com/support". I also tried to connect with iTune. But it again says.."We're sorry, we are unable to continue with your activation at this time. Please try again later, or contact customer care". I had repeat this process for several time but no progress at all. Can you help me please?

Thanks in advance.