Siemens: Secret Codes and Tricks for All Vintage Models — Complete Guide 2026

This is the definitive guide to Siemens secret codes for vintage phones. Siemens has a unique system — from the S1/S3/S4 series with Monitor Mode activatable via numeric sequence, to the S55/C65/S65 series with advanced engineering menus. This guide includes very rare codes like the manufacturing date, monitor mode, the White House number easter egg and the *#SIEMENS*TEST# test mode.

How the Siemens Code System Works — Read First

  1. Direct codes *#XXXX# — entered from the main screen
  2. Menu sequences — navigation through the phone menu
  3. Language codes *#XXXX#+green key — immediate language change

Fundamental difference: many Siemens codes require the green key (call) for confirmation, not just #.

Universal SP unlock code: *#0003*[8 digits]# — the 8 digits are IMEI-specific, not universal.

Universal Siemens Codes

Code Function
*#06# Display IMEI code
*#06# + green + left softkey Software version + IMEI (S3/S4 models)
*#0606# SP lock status — without SIM shows secret code
*#0606# + left softkey Check lock — characters + lock status text
*#0003*[8 digits]# SP lock removal (IMEI-specific)
*#0000# + green Reset language to automatic
*#3370# Enable Enhanced Full Rate
#3370# Disable Enhanced Full Rate
*#4720# Enable Half Rate (battery saving)
#4720# Disable Half Rate
Menu 8-8-2 + left softkey Software version

Language codes (with green key):

  • *#0000# + green → Automatic | *#0001# + green → English
  • *#0032# + green → French | *#0034# + green → Spanish
  • *#0039# + green → Italian | *#0049# + green → German

Reading Lock Status with *#0606# — Full Explanation

With SIM + left softkey: first hexadecimal characters of the EEPROM lock, then lock status text. "brak blokad" = no locks active (Polish text from firmware bug). Code like "234-30" = locked to MCC 234 (UK), MNC 30 (T-Mobile UK).

Siemens C25 — Full Secret Codes

The Siemens C25 (1999) — one of the most rugged phones ever produced. Unmatched German build quality.

IMEI: *#06# | SP lock: *#0606# + left softkey | SP unlock: *#0003*[8 digits]#

Language: *#0000# + green | English: *#0001# + green

EFR: *#3370# / #3370# | Half Rate: *#4720# / #4720#

Software version: Menu 8-8-2 + left softkey on IMEI display

C25 Pinout (very rarely documented):

  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

Useful for repairs and accessory manufacturing.

Easter Egg — White House number: In the phonebook under 'Own number', enter +12022243121 with any name. After restart, sometimes a developer surprise appears.

Extend battery life:

  • Disable automatic network search (Menu 6-3) in fixed signal areas → saves 15-20%
  • Disable IrDA when not needed
  • Disable vibrator when not necessary

👉 View Siemens C25 available at Infosate

Siemens S25, M35, S35, C35 — Secret Codes

The S25/M35/S35/C35 family (1999-2001) — first Siemens generation with GPRS (S35i).

IMEI: *#06# | SP lock: *#0606# + left softkey | SP unlock: *#0003*[8 digits]#

Language: *#0000# + green | EFR: *#3370# / #3370#

Monitor Mode S35 — activation: Menu → 9 (Settings) → 8 (Phone Status) → IMEI visible → left softkey × 2 → 98 → left softkey → 7684666 → red key (hang up)

Monitor Mode is now active. To view information: Left softkey → 5 (GSM Service) → 6 (Monitor)

Shows in real time: Cell ID, LAC, MCC, MNC, signal strength in dBm, RF channel, signal quality. To deactivate: switch phone off and back on.

Manufacturing date (menu 10):

  • Menu 10.3.2 → Manufacturing date
  • Menu 10.3.3 → Service date
  • Menu 10.3.4 → Repair date
  • Menu 10.2.1 → Software version
  • Menu 10.2.2 → EEPROM version

👉 View Siemens S35 available at Infosate

Siemens S45, ME45, S45i — Secret Codes

The Siemens S45 (2001) and ME45 (2001) — the ME45 is famous for its military-grade durability (IP54) and was used by Jason Bourne in "The Bourne Supremacy".

IMEI: *#06# | SP lock: *#0606# + left softkey | SP unlock: *#0003*[8 digits]#

Language: *#0000# + green | EFR: *#3370# / #3370#

Monitor Mode S45/ME45: Menu → 9 → 8 → IMEI → left softkey × 2 → 98 → left softkey → 7684666 → red key Then: left softkey → 56 → Monitor Mode active

View data: left softkey → 5 → 6

Manufacturing date: Menu 10.3.2

S45 → S45i upgrade: the S45 could be updated for free to S45i (with email client). *#06# + left softkey shows firmware version.

ME45 authenticity check: Original ME45 has matte black anti-slip casing (not the glossy S45 casing). IP54 certification: 1.5m concrete drop, dust and water splash resistance.

Easter Egg — "Jason Bourne's phone": In the 2004 film "The Bourne Supremacy", Jason Bourne uses a Siemens ME45.

👉 View Siemens ME45 available at Infosate

Siemens S55 — Secret Codes

The Siemens S55 (2002) — first Siemens with integrated Bluetooth.

IMEI: *#06# | SP lock: *#0606# + left softkey | SP unlock: *#0003*[8 digits]#

Language: *#0000# + green | EFR: *#3370# / #3370#

Monitor Mode: same procedure as S45

Bluetooth MAC address: Bluetooth menu → Bluetooth settings

👉 View Siemens S55 available at Infosate

Siemens C65, S65, CX65, M65, SK65 — Secret Codes

The 65 series (2004) — colour CSTN/TFT display, integrated camera, advanced GPRS.

IMEI: *#06# | SP lock: *#0606# + left softkey | SP unlock: *#0003*[8 digits]#

Language: *#0000# + green | EFR: *#3370# / #3370#

Test mode (very rare): *#7436267*8378# (*#SIEMENS*TEST#) Hold red key until code disappears. Opens:

  • Menu 3.3.4 → Frequency selection (Automatic / GSM-900 / GSM-1800)
  • Menu 10.1 → MS info | Menu 10.2.1 → Software version | Menu 10.2.2 → EEPROM version
  • Menu 10.3.1 → Hardware data
  • Menu 10.3.2 → Manufacturing date ← very rare
  • Menu 10.3.3 → Service date ← very rare
  • Menu 10.3.4 → Repair date ← very rare

Menus 10.3.2/10.3.3/10.3.4 = Siemens equivalent of Nokia Warranty Codes — show when the phone was manufactured, serviced and repaired. Almost no website documents these menus.

Frequency selection S65: *#SIEMENS*TEST# → Menu 3.3.4 → force GSM-900 improves reception in 900MHz areas.

SP65 vs S65: SP65 = corporate version without camera. Firmware version visible with *#06# + left softkey.

LCD chip identification:

  • LPH88xxxx → Hitachi HD66773 | LS020xxx → Sharp | L2F50 → Epson L2F50 Menu 10.3.1 shows hardware data including LCD type.

CX65 MMC support note: CX65 officially supports MMC up to 256MB but works unofficially with cards up to 1GB (SanDisk MMA 7-pin certified only).

👉 View Siemens C65/S65 available at Infosate

Siemens S4 and S4 Power — Historical Monitor Mode

Monitor Mode S4 (full procedure):

  1. Switch phone on, enter PIN if required
  2. Press Menu (upper left softkey)
  3. Press 9 (Phone Options)
  4. Press 8 (Phone Status) — on some models it's 7
  5. IMEI number appears
  6. Press left softkey
  7. Type 7684666
  8. Press red key (hang up)
  9. Monitor Mode is now active — "Monitor" appears at bottom of Network Options menu

Read Monitor information: left softkey → 5 → 6 Shows: dBm signal strength, Cell ID, LAC, MCC/MNC, RF channel, top 6 cells with strongest signal. To deactivate: switch phone off and back on.

Easter Egg S4/S4 Power: In the phonebook under "Own Phone No." enter +12022243121 (US White House number) → developer greeting appears.

Software version S4: With SIM removed: *#06# + left softkey → shows software date. With SIM inserted: Menu 9 + 8 + left softkey twice.

Siemens S6, S8 — Historical Easter Egg

Easter Egg S6/S8: In phonebook under "Own Phone No." enter +12022243121 with any name → special greeting from Siemens developers.

Siemens S10, E10 — Easter Egg

Easter Egg S10/E10: Enter +12022243121 as your own phone number in the phonebook → a picture with sun, two palm trees and a greeting from the developers appears.

Siemens S1/S3 — Monitor Mode (older models)

Monitor Mode S1/S3: Menu → 9 → 7 (Phone Status) → left softkey → 5553756 → red key

(Different access sequence from S4 — 5553756 instead of 7684666)

Universal GSM Codes — All Siemens GSM

PIN/PUK: **04*[old]*[new]*[new]# | PUK: **05*[PUK]*[new]*[new]#

Call forwarding: ##002# cancel all | *#21# check | **21*[number]# activate

Call barring (default 0000): *33*(password)# outgoing | *353*(password)# incoming

Private number: #30#[number] hide | *30#[number] show

Frequently Asked Questions

What does *#0606# show exactly? With SIM + left softkey: hexadecimal EEPROM lock characters, then lock status text. "brak blokad" = no locks. Code like "234-30" = locked to T-Mobile UK.

Is *#0003*[8 digits]# universal? No — 8 digits are IMEI-specific, calculated via Siemens algorithm.

What does 7684666 mean in Monitor Mode? Engineering access code for the S4/S35/S45/S55 series. The S1/S3 series uses 5553756 instead.

Does Monitor Mode deactivate automatically? Yes — deactivates when phone is switched off and back on. Not permanently saved.

What is the default Siemens phone code? Most vintage Siemens phones use 0000 (four zeros) as the default phone lock code.

Original Vintage Siemens at Infosate

At Infosate you'll find a selection of original vintage Siemens phones — C25, ME45, S55, C65, S65 and other iconic models from the German brand, all verified before shipping.

👉 Explore the Siemens collection at Infosate

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