How can we track UE in LTE?

Question

How government individual tracks suspicious UE in LTE ?which entity is responsible for this tracking,can they block UE (like UE should not able to use any other SIM and which entity is responsible to this)

Answer 1

There are two permanent identities in the network. One is IMEI and other one is IMSI. Before cell phone comes to market for sell, each UE is tagged with an identity which is used to track cell phone if required. IMSI is associated with each operator and when you buy a SIM you get MSISDN number and SIM will be having associated IMSI in the network database.
Whenever intelligence agency wants to locate a cell phone, first they track based on MSISDN, if they not getting expected result then they move to IMEI. Most of the times, criminals change the SIM but they can not change IMEI of cell phone.
There is one node in LTE network known as Equipment Identity Register (EIR). This node is used to control the access of devices based on their IMEIs.

Reference:
http://www.mavenir.com/our-products/mobile/equipment-identity-register