Factory SIM unlock code of HTC 6900 is available, means permanent unlocking of HTC 6900 is possible using a correct NCK code. We can unlock all HTC easily by IMEI. There is no need to change the firmware to unlock it if the phone prompts for an unlock code after changing the SIM card. Unlocking of HTC 6900 by the code is the recommended method as you will not loose the warranty of the phone. It is the fastest and secure method to unlock the phone by IMEI code. An unlocked phone can be used with all networks SIM card around the world.
The unlocking of the HTC 6900 by code is a recommended method by the manufacturer. Since the unlock code comes from manufacturer database, it will unlock your phone 100%.