I have updated my software on my iphone 3?

After updating the software on my iphone 3g in order for it to be compatible with most of the apps on itunes, I have tried to connect it to my wireless network to continue with the activation where it repeatidly tells me that 'your iphone cannot be activated at this time because the activation server is temporarily unavailable'. I have also tried connecting it to itunes to also try to continue with the activation where it also tells me 'we are unable to continue with the activation at this time'. However since i purchased my iphone 3g, the sim card has not been read and says 'No Service' at the top left corner of my screen, please help. Thank you.