We accept no responsibility of any kind for damage done to your phone whilst trying these codes.
All Siemens Phones: Service Provider Unlock: *#0003*(secret code 8 digits)#

Siemens S25/C25

SP unlock *#0003*(secret code 8 digits)#
Show IMEI code: * # 06 #
Resets language to automatic selection : * # 0000 # then Green button
Pin Out
Data Cable schematics
Phone's connector pin-out:
1- GND
2- SB
3- POWER
4- NC
5- TX
6- RX
7- CLOCK
8- DATA
9- GND MIC
10- HF MIC
11- AUDIO
12- GND AUDIO

Siemens S1/S3/S3 Com

To view the software date and else with S3 com, S4, S4Power, Sony cmdx 1000e press with SIM removed *#06# and left softkey.
To view some other stuff with S4Power, Sony cmdx 1000e press with SIM removed *#06# and left softkey twice.
To view the software date with S3 com, S4, S4Power, Sony cmdx 1000e press with SIM installed menu 98 and left softkey twice.
ACTIVATE MONITOR MODE
Siemens S1/S3

Menu, 9 (Phone Options), 7 (Phone Status), Left Display Button (left MENU key), 5553756, Hang-Up Button (Red Handset key)

Siemens S3 COM/S4

Menu, 9 (Phone Options), 7 (Phone Status - 8 on Some), Left Display Button (left MENU key), 7684666, Hang-Up Button (Red Handset key)

Note: Now Monitor should appear at the bottom of the Network Options menu.