Original Thread by westnz
Requirements : ATIV SE running latest WP8.1.1 (Update 1) Build and following files
https://mega.nz/#!CMVziZIL!w1fdfgb2m5S8sonW51O5BFhhX3R5tWyl1AhfYceS9w8
https://mega.nz/#!2RVlwJKR!LR0JL_b0M5apY0Vijxq1MMn5BogUtFqbO3wPd21RbW8
1. Factory reset your phone. ( if needed )
2. Do setup. Connect to Wi-Fi, select custom, uncheck auto update apps.
3. Unlock your phone via Windows Phone 8.1 Developer phone registraiton.
4. Go Settings, date+time, set date 100 years forward. ( no reboot needed )
5. Go back to Settings, scroll down and click call/message settings.
6. An error popup occurs. Proceed uninstall.
7. Then set date+time back correctly.
8. Copy InteropUnlocker_SE_81.xap & wphTweaks_v10.xap into the root of SD card.
9. Create a blank txt file and rename it Non-Production Errors.txt
10. Copy the txt file you just created to Documents folder in the phones memory.
11. Using SDK, deploy SamWPSystem to phone memory.
12. Go Storage Sense, change where to store new apps to SD card.
13. On app list, open CustomWPSystem.
14. Click SD Card permissions box, tick sd card and press OK icon.
15. Click Unhide WPSystem too. Two of items will be green then.
16. Select AdditionalCallSettings as the target app and press Download from Store.
17. After install it again, go back to CustomWPSystem.
18. Select the XAP > sd card > InteropUnlock_SE_81.xap and go apply XAP.
19. Open Settings, scroll down to the bottom, run additional call settings.
20. Hit Unlock. When it succeed, reboot the device.
21. With SDK, deploy wphTweaks.xap
22. Open WPH Tweaks > tools > tap registry editor.
23. Follow OP's guide by step 16.
( You can browse the item with double click )
Well... did I follow right steps?