TS3424: iPhone: Troubleshooting activation issuesLearn about iPhone: Troubleshooting activation issues
Currently Being ModeratedApr 5, 2013 1:27 AM (in response to mdsjayathunga)
It happens to a jailbroken iPhones or to the ones which were unlocked unofficially. After the Restore/ Update in iTunes, the iPhone gets locked again to original carrier. Inserting SIM in the iPhone from original carrier would help.
Currently Being ModeratedApr 5, 2013 2:05 AM (in response to mdsjayathunga)
"We're Sorry, Activation Server Temporarily Unavailable, contact Customer Care?"
99.9% of the time, the cause of this issue is the fact the phone was jailbroken/hacked to unlock it for use on networks other than the network the phone was originally locked to. Apple maintains a database of officially unlocked iPhones, and when Apple's servers detect phones such as yours, activation stops & you get the message you got.
So, either get a sim card from the carrier your phone was originally locked to, or get it officially unlocked, if you want to activate it. Because it appears that it was not officially unlocked.