How to block mobile signal - umts signal blocker in history

How to block mobile signal,umts signal blocker in history,d_10px pad_l_28px big allborder"> Product Specifications: Car GPS Signal Jammer 3 To 6 Meters Coverage Main Feature: Car GPS Jammer 3 To 6 Meters Coverage Working Band: L1 system 1450 to 1600Mhz ...