How imei network sim locking works

How mobile imei and network sim locking & unlocking working principle.


Here I explain how mobile locking done at imei level by sim network service provider.
           Lg, Samsung, Nokia, Motorola all mobile companies spend millions on research and development. Nowadays every month’s new mobile launch and most of the time this mobile sell with carrier locked condition. Then people start looking for imei unlock codes for lg, Nokia, Samsung, Huawei, htc, acer and Motorola.

          Before continue here is a brief detail of imei no.
           Imei stand for International Mobile Equipment Identity. It is 15 or sometime 16 digit number. Each mobile has unique imei number.

   Mobile Imei number consist of 4 part. 

  •   tac/type approved code which is of 8 digit,
  •   Final assembly code /fac, 
  •   Serial number/snr  this is assigned within tac,
  •   Spare digit /sp. 
 imei = tac & snr + fac +sp = 15 digit.
 If you have proper knowledge of mobile locking. Then you can easily carrier unlock it from imei generated network unlock code. At other post I have explained that how mobile unlocking done without unlocking codes. And I have given all details about Samsung network unlocking at android level without unlocking codes.

        First understand that your mobile identity on gsm carrier network is imei no & not mobile no. Furthermore when you insert sim inside lg, Samsung or Nokia. Mobile immediately starts searching for available all gsm sim networks around phone vicinity. It find appropriate carrier network and register on that network with imei number. So it is clear that locking and unlocking done on imei no.
       If mobile is network unlocked then it can search all available gsm network and it can access all sim network. But if mobile is locked then it can search all gsm network. But it can access only 1 sim network. And when it tries to access other sim network. It asks for sim unlock code created from imei no. This imei unlock code hidden inside android operating system software.
                Gsm sim provider network is nothing but a frequency/ band assigned to each gsm sim provider. This is called mnc / mobile network code.  Also in mobile network, every country has its own code which is called mcc/ mobile country code. Mnc and mcc is needed for generating imei unlocking code for lg, Samsung, Nokia and Motorola.

Below is the list of few mobile country code/mcc  and mobile network code / mnc.

 United Arab Emirates mcc : 424,   mnc for du company : 03.
united kingdom  mcc : 231,   mnc code for orange : 33,  mnc code for tmobile UK :30.
usa country code mcc :310,  mnc code for Verizon : 005, mnc code for at & t in USA:  660, mnc t-mobile :  670.   
                  When mobile is locked, this locking code block mobile to access other sim network. Like we have manual or automatic network selection option in many old Samsung, Nokia, Motorola, lg mobile phone.
                Now you can understand why imei no is needed for generating mobile network unlock codes. That is why it is also called lg imei unlocking code and not only lg unlock code.

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