APAC Service - iPhone 4/4S/5/5S/5C (Premium Service)
APAC is an abbreviation for Asia Pacific, which is a regional designation used for government, marketing and business purposes. A few years ago, some networks works together with Apple and brought the iPhone to customers in East Asia, Southeast Asia, and Oceania markets. iPhones sold there may have their carriers marked as APAC in the Apple’s database, and may not necessarily be tied to a specific carrier.
To know if your phone can be considered as APAC you just need to run the IMEI on the tool iPhone Carrier and Sim-Lock Status- GSX details and if the result show "Next Tether Activation Policy Description: APAC Service" then you can unlock this phone using this service.
WARNING: If you don't check properly the phone and the Next Tether Activation Policy is different than APAC will not be able to give you a refund!