LAHORE - Pakistan Telecommunication Authority made extraordinary efforts to curb illegal issuance of SIMs and to ensure authentic antecedents of mobile subscribers by implementation of one of its kind Online Verification of Mobile Subscribers Antecedents through NADRAs Database -789" in February 2009. After having successfully implemented the system for mobile operators, PTA has extended its efforts by brining the WLL operators under the same umbrella. In this regard, Chairman Dr Muhammad Yaseen has inaugurated the call centers of M/S Worldcall here at Lahore.