AT command for sending MMS has no standard. For sony ericsson : AT*EAPP=6 and not all sony ericssyon support this command (and i never found the support one, you can check it by AT*EAPP=?). The simplest way is try redo the way when we want to send MMS manually by pressing keypad, and note how long response when enter each menu. Then you can simulate the pressing keys by AT command. Send this command AT+CSCS="8859-1" <CR> before then follow by next at command for each key.