Home Location Register (HLR) contains information in regards to approved subscribers utilizing a global system for mobile communication (GSM) core network. The home location register stores data going from telephone numbers to the current location of the user. HLRs do exclude data about endorsers that have a place with the Mobile Network Operator’s (MNO’s) roaming partners. Home Location Registers don’t follow endorsers’ locations continuously. The network intermittently transmit Tracking Area Updates (TAUs), which advise associated devices to share their location.