TMSI Technique to Imei Unlock Mobile Sim card

This website is about using tmsi to carrier network unlock mobile. Here it requires to understand few telecommunication terms. Then only you can grasp how this emergency call tmsi is used to unlock sim.

TMSI is temporary mobile subscriber identity. Each mobile has unique IMEI number. International Mobile Equipment Identity.

IMSI International Mobile Subscriber Identity number. IMSI consist of mobile country code, mobile network code and MSIN Mobile Station Identification Number.

MSIN is used to identify different mobile carrier operator. For example in USA major network carriers are at&t, t-mobile, Sprint and Verizon. Each of these operators has their distinct mobile country code and mobile network code.

       Each mobile carrier network operator has its own field site in every city where operator provide network. They install many nodes / base station to provide network in particular area. Each network carrier has visitor location register. So when we move from one area to another area, our mobile register on different nodes or base station of wireless sim network operator.

      Now to protect mobile user privacy, mobile which register at this node will be given TMSI temporary mobile subscriber identity. So imei or imsi number will be hidden. This to avoid disclose of identity of mobile user.

 Now emergency call has different angle for this. When you call an emergency number, if mobile carrier network is not available. Even though you can talk with the emergency number. For emergency number whatever network available in your area will be used to connect. It is rules for telecommunication network operator that when they get call request from any device it must be allowed to connect.

     For example if you are in Canada. Major carrier are bell, telus, roger. Now if you try to make call from roger and if roger network is not available. Then you call must be served by other network operator. You can register to other network but you have very limited access to that network, or we can say it is just for emergency number only.

       Now emergency call using TMSI. This hack is used to imei unlock mobile. Mobile sim restriction cab be removed by sim unlock code which can generate from imei number. But here sim adaptor is used to unlock mobile using tmsi. Now sim adaptor is placed with mobile sim card in same sim slot. Now when mobile try to register on network this adaptor modify information. so mobile baseband model and network carrier are not able to recognize that mobile is sim locked. They use tmsi to make calls.