One way to quickly identify "test calls" or "ghost calls", which are the calls that cause your SIM cards to be blocked, is to check their validity in the HLR (home locator regiister). Much of the time, the "anti-fraud" companies like SIGOS and Araxxe are not competent enough to properly register their target SIM cards in the mobile network's HLR, so a quick verification will show that the SIM is "dead" and we can conduct this check in real-time as the call is connected. This will significantly improve your SIM lifetime average.
A single HLR check is priced at $.0074. You can buy as many or as few as you would like. (*not available in call countries. Contact us to check availability. Discount for bulk purchasing over 300k checks)