Service codes "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
and more:
*#77218114#
*#19992006# dd
*#881188#
#*94267357#
khoi phac lai he thong -> mã là 1122
*#3646633#
*#33778#
S500 *#77218114#
C600 *#881188#
*#19992006#
#*94267357#
*#881188#
*#77812114#
*#19992006#
*#9426*357#
*#0084# call
*#0000#, *#0044# Default English
*#0086#, *#0886# set to China
*#0084#, *#0966# set to Vietnamese
*#77218114#
*#19992006#
*#881188#
#*94267357#
*#77218114#
*#0000#, *#0044# Default English
*#0086#, *#0886# set to China
*#0084#, *#0966# set to Vietnamese
*#77218114#
*#0084#call
moden s500:reset*#881188#
----------------------------------------------------------------------------
*#19992006#
*#881188#
#*94267357#
*#77218114#
*#9426*357#
*#9426*357#
*#0084# call
*#0000#, *#0044# Default English
*#0086#, *#0886# set to China
*#0084#, *#0966# set to Vietnamese
*#77218114#
*#19992006#
*#881188#
#*94267357#