KT/SK Korea, APAC iPhone 3G/3GS/4/4S/5/5S/5C Semi Premium (Success Rate 80%)
Delivery Time: 1-5 Days
If your imei is clean, but can not be done under kt / sk clean imei service, then it probably be unpaid bill phone. You can submit under this service.
This service usually takes 3-7 working days.