China Mobile Secret Codes
Default user code : 1122, 3344, 1234, 5678
Engineer mode : *#110*01#
Factory mode : *#987#
Enable COM port : *#110*01# -> Device -> Set UART -> PS Config -> UART1/115200
Restore factory settings : *#987*99#
LCD contrast : *#369#
Software version : *#800#...