Thank you very much to everyone with bring me help, really thank you.
The solution is this for another users:
1-Download the file for this link: http://pastebin.com/yjcmxqpm
2-save the .txt file in the SD
3-install the ES file explorer, you must root to copy st15a.txt file into System folder.
4-copy st15a.txt file and rewrite the file to build.prop and cut the original build.prop file to SD.
5-restart your phone, look in settings, your phone now is st15a.
6-Optional. Make a factory reset if you will, after that your phone still be st15a.
Thank you very much to ahzoe user for the idea/recommendation.