The application sends SMS commands in a special format to the GSM module, with the help of these commands you can access all module settings, incl. list of authorized users management, module system settings, etc. Supported GSM modules: ELfoC C1, ELfoC C2, ELfoC C3, ELfoC B1, ELfoC B2, KATOLA US200-1, KATOLA US200-2, KATOLA US1000-1, KATOLA US1000-2