Here is a method (confirmed working by Me) to SIM Unlock your HTC ONE M8 GSM ONLY NOT FOR SPRINT for other SIM cards for use on other GSM networks.
Before we begin I wish to inform you that I did not create this tool. It is the property of sieempi.
You MUST be S-OFF & have External SD for this to work.
S-OFF METHOD or http://theroot.ninja/ if you can't S-OFF with first method
Usual disclaimer: I am not responsible for anything you do to your phone. Use this mod at your own risk.
SUPER CID WILL NOT SIM UNLOCK YOU DEVICE FROM CARRIER
how to SuperCID your device after S-OFF
[NOOBS Guide] HTC ONE SUPERCID method via fastboot
or permanent method
1) Go to this site: http://www.sieempi.eu/blog/2011/09/2...tc-devices-536
2) You'll notice that the HTC ONE M8 is not listed in the supported devices, but the process does work.
3) Supply a valid IMEI and email address on the form on that page and where it says "Phone Type" put HTC ONE M8 , and they will email you a Config.Dat file to put on the root of your EXTERNAL SD card.
4) Reboot into bootloader, select "SIMLock" and it'll apply the config file.
5) Follow the instructions on the phone and reboot when it tells you to. If you get an "OpenCID File Fail" error, this is normal, proceed anyway!
6) Once you've rebooted, your HTC One M8 should be fully SIM Unlocked!
7) Put in a foreign SIM card and test it out
If you have any questions, please refer to the linked site as I will be limited in how I can help since I am not the original creator of the tool.
Adrian Campeanu (sieempi) - for the tool, because you know, it's his intellectual property and stuff
Binary - for sharing the site that has the tool and for risking his device to make sure it works (THANKS!!! )
PS. I encourage donations to the tool maker who actually created this tool. You can find his donation button on the linked unlocking site.
This info was taken from this HTC Amaze forum thanks to @electronicrice for putting together the original thread that can be found here