Q: is activation server down?

According to Apple http://www.apple.com/support/systemstatus/, no. What are you seeing regarding the activation server? What error is on the device or iTunes?

There are four primary causes of the activation error:

• The activation server is unavailable. Rare, but it happens. Usually fixed within minutes.
• Your antivirus or firewall (or your router's firewall) is blocking access to the domain gs.apple.com on ports 80 and 443.
• Your phone is jailbroken.
• Your phone isn't jailbroken, but the computer you are connected to during the restore or update was used to hack or jailbreak some other iOS device, and its network database was corrupted in the process.

Perhaps this will provide you some clues as to how to proceed. If your iPhone has not been jailbroken, Apple has some troubleshooting suggestions here:

http://support.apple.com/kb/TS3424 

If your iPhone has been jailbroken, you're on your own. We can provide no assistance for jailbroken devices in these forums.

Regards.

(part of the above information quoted with gratitude from Lawrence Finch)

just keep tr your iphone will activate .for me 3 days to activate and go to c/ windows system32 driver host add gs.apple.com save reconnet iphone to itunes will work pro ( iphone 4 ios7.1.2)