Do you hold the red phone button + C + green call button + lock button at the side of the phone when the IMEI message pops up?

Press and hold these 4 buttons,
Star-3-green-red. You have to hold them for a few seconds.
(* - 3-call button- power button)

Or try this

tap this numbers: *#7370#
Then accept information in your screen -> press Ok.
Now if you have, enter your security code.
* The default code is 12345

UNLOCKING PHONE
Hi you can use codes to unlock the mobile . to get the unlock codes visit this link:http://www.unlocking4free.com/
Here they ask the following details before rendering the unlock codes they are 1. Mobile model 2. Country from where you brought the mobile 3. Provider to which the mobile is locked 4. Imei number of the mobile Finally they will send you the unlock codes at free of cost.once you entered the code in your mobile as for the instruction given by them .your mobile get unlocked and it accepts any network sim to get the IMEI: UnlockPhone Via IMEI. Your phones IMEI is your unique number that is given to eachphone. For each IMEI there is a unique unlock code that once entered into your phone will enable you to use any compatible sim card. You can get theIMEI for your phone by entering*#06# into your keypad. You will only need 1 unlock code to enable you to use any sim card in your phone and enable it to be "network sim free".
you can also try going to this site:http://www.foneszone.co.uk/unlock_codes/ though this site may not guarantee a free service..

or you may try one of this:
reformatting NOKIA Series phone:
simple ways to format your Nokia NSeries cell phones.
(Please do remember that some of the steps below will clean up all your data in phone so remember to make up backup copy of it. Otherwise you will end up loosing them forever.)
Method:1
1. Switch off the phone.
2. Hold down the following three buttons: Green (call answer button, * button, and '3? button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message 'Formatting' appears on the screen, release all of the buttons.
Method: 2 ( Hard Format)
1. Switch off the phone.
2. Hold down *#7370# button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message 'Formatting' appears on the screen, release all of the buttons.
Method: 3 Soft Reset
1. Switch off the phone.
2. Hold down *#7780# button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message 'Formatting' appears on the screen, release all of the buttons.
http://techalites.com/2008/05/06/how-to-format-nokia-n72-n73-n81-n95-nseries-phones/
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Hi, you can get the code here for FREE*) :
www.nfader.su
kind regards, vote please, Jay__GT

*) need to key in your IMEI #

1. Switch off the phone.
2. Hold down the following three buttons: Green (call answer button, * button, and ‘3′ button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message ‘Formatting’ appears on the screen, release all of the buttons.
Method: 2 ( Hard Format)
1. Switch off the phone.

turn off your phone.when you switch it on hold the *,green and 3 button simultaneously .remember *(star),green and 3 button. hold these three buttons and switch on your handset, it will be formatted without the lock code option and your lock code will turn to default.
good luck

turn off your phone.when you switch it on hold the *,green and 3 button simultaneously .remember *(star),green and 3 button. hold these three buttons and switch on your handset, it will be formatted without the lock code option.your lock code will turn to default.
good luck

Press and hold "ICE MAKER LOCK" button, and while holding it shortly press "LOCK" button, and the light will change to green LED.

the defualt sercurity code is 12345, there is no other code,
you can perfome a master reboot of the phone with out the sercurity code my pressing and holding (3,* and the green call button) and powering the phone up keep holding the buttons untill you here the nokia tune, this will reset the whole phone, contact, photos, callander all will be lost so backup first.
but his will get around a security code but not a sim lock or imei lock.

Siemens Mobile Secret Codes:

C25:
SP unlock *#0003*(secret code 8 digits)#
*#0606# shows you Secret Code, but only without SIM Card.
*#06# for checking the IMEI (International Mobile Equipment Identity)
How to change PIN:
**04*old PIN*new PIN*new PIN#
How to check simlock status
*#0606# and then press left soft-key, you will see strange characters, then text ("brak blokad"). If you see for example 260-02, it means the phone is locked to Era GSM. In older models you can use *#06# and see the same information after clicking on left key (you will see IMEI and software version).

S4:
Monitor Mode - how to activate:
Press left soft-key, then 9 (SET UP) 8 (Phone Status). You will see IMEI number, then press left soft-key and in order 7684666 and red phone at the end (monitor mode has been activated). To read information from Monitor Mode - press left soft-key, then 5 (GSM SERVICE) and 6 (Monitor). Monitor mode turns off when you switch off the phone. You must activate it again if you want.
How to see date of software:
Press left soft-key, then 9 (SET UP) 8 (Phone status). You will see IMEI number, then press twice left soft-key, 98, left soft-key, 7684666, red phone (activates Monitor Mode), left soft-key, 56 (turns on Monitor Mode), left soft-key, 98, left soft-key, 7684666, hang up (red phone) >abck to "normal" and then left soft-key, 56.
S6, S8:
If you add to phonebook under 'own phone number' +12022243121 with namez (for example MMI), then you will see something smile.gif
S10, E10:
In phonebook enter +12022243121 as your own phone no. You will see a picture with sun, two palms and greetings.
S15e:
Monitor Mode:
Code: *#7436267*8378# (*#SIEMENS*TEST#)
Hold red phone button until it code disapears.
Menu 3.3.4 Choose frequency.
Menu 3.3.4.1 Automaticaly.
Menu 3.3.4.2 Choose GSM-900
Menu 3.3.4.3 Choose GSM-1800
Menu 10.1 MS info
Menu 10.2 Soft date
Menu 10.2.1 Software version.
Menu 10.2.2 EEProm version.
Menu 10.3 Tst and product info.
Menu 10.3.1 Handware data.
Menu 10.3.2 Date of manufacture
Menu 10.3.3 Service date
Menu 10.3.4 Date of repair.

S25:
Enhanced Full Rate
*#3370# turns on
#3370# turns off
Haft Rate Mode
*#4720# turns on
#4720# turns off.
Languages:
*#0000#+green phone - choose automaticaly
*#0001#+green phone - English
*#0030#+green phone - Greek
*#0031#+green phone - Netherlands
*#0032#+green phone - French
*#0034#+green phone - Spanish
*#0039#+green phone - Italian
*#0049#+green phone - German
*#0090#+green phone - Turkish
How to change PIN2?
**04*old PIN2*new PIN2*new PIN2#
What is my software version?
Menu 8-8-2 press left-softkey when you see IMEI number, or *#06# and then green phone button and then press left soft-key.
How to extend battery life:
IrDA - turn on only when you need.
Turn off automatic network search (6-3)Turn off Vibration alarm.
SP unlock *#0003*(secret code 8 digits)#
*#0606# shows you Secret Code, but only without SIM Card.
*#06# for checking the IMEI (International Mobile Equipment Identity)
Resets language to automatic selection : * # 0000 # then Green button

S25, M35, S35, C35
SP unlock *#0003*(secret code 8 digits)#
*#0606# shows you Secret Code, but only without SIM Card.
*#06# for checking the IMEI (International Mobile Equipment Identity)
Resets language to automatic selection : * # 0000 # then Green button