CHINESE MODELS:
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#
software version: *#900#
set default language: *#0000# Send
set English language: *#0044# Send
set English language (new firmware): *#001# Send
Service codes **x, 5xx:
software version: *#79#
software version: *#837#
Service codes VK200, VK2000, VK2010, VK2020, VK4000:
software version: *#79#
service menu: *#9998*8336# (hold #)
reset defaults (phone/user code reset to default): *#9998*7328# (hold #)
