Location Update results due to two major causes in GSM system. One is when MS changes from old LAC to new LAC and the second is when the network specifies MS for periodic location update. Network controls the location time interval and depends upon T3212 timer. Network broadcasts to all MSs in the cell via “RIL3_RR SYSTEM INFORMATION TYPE3” message. T3212 timer is one of the system control parameters. In ZTE system it value is in deci hours. I deci hour = 6 mins.
Value of 3212 can be – 4 hours.