Wonde Proud M7 / Navixy M7 "Default Password"

Good afternoon colleagues, I have the following question to see if I can help, I have approximately 5 units model Wondex Proud M7 (portable tracker) of a client, I have the SMS commands to configure them the SIM card has balance and works correctly, but when you do, use the default password "0000" but this does not respond the sent commands. You may have a key other than the default and if so, is it possible to change it?