A method and apparatus for managing TACs and TAIs used in communications system is disclosed in which “associated TACs” are used on a global basis and “unassociated TACs” are used on a regional basis. Associated TACs are associated with International Mobile Subscriber Identify (IMSI) Bin Numbers (IBNs). The value of each associated TACs is determined based on an associated IBN that serves as a seed for generating the TAC value. Unassociated TACs are TAC values that are within the “TAC space” of valid TAC values, but that are not within the pool of associated TACs. In some embodiments, there are 60,000 associated TACs and 65,536 total TAC values in the TAC space. Therefore, in such embodiments, there are 5,536 unassociated TACs that are regionally managed.