After reset, my iPhone cannot be activated
Hello
After reset my iPhone(erase all content and setting), my iPhone cannot be activated.
An error message appears from iPhone:
Activation Error
Activation request could not be completed. Please press the home button to try again. If the problem persists, please contact customer care.
An error message appears from iTunes:
We're sorry, we are unable to continue with your activation at this time.
Please try again later, or contact customer care.
Even try to change another SIM card, change DNS server, using VPN and activate via WiFi and latest version iTunes.
I don't want to upgrade my iOS version. I am pretty sure my hardware and software have no issue.
Most people have same issue. Please help to resolve this problem, thanks.
iPhone 6s, iOS 9.2