CDMA S5 unlocked to work on other GSM carriers

[AC Question]

I have a S5 (SCL23) it seems that it was originally for a CDMA carrier. I am wondering how to unlock it so that it will work on other carriers, mostly GSM. I have tried to use the sites where you order the unlock code over the internet, and found that the one I tried is a scam. I found a guide to unlock the phone via codes entered in the dial screen. and they seem to have made it able to be used as I can make phone calls, but it will not automatically populate the APN for the sim card installed so I have no internet. so now I am looking for another option. Any sugestions? can I use odin to change it to an international version? or a GSM version?