With the growing proliferation of technical gagdets the pains of security are being felt by more and more users – it used to be your PC which was often fell victim to hackers or viruses. The next big thing seems to be cell phone – more ubiquitous than PCs, cell phones are subject to fraud, hacking and of course plain old fashioned crime — stealing. Depending on your location one of the above security issue may be a higher priority than others. In Pakistan cell phones have always been popular with street robbers. Even in some parts of London theft of mobiles accounts for 35% of street robberies! Now the trend has evolved to hacking that is cyber robbery – identity theft or prepaid card balance theft. It was reported in the news that “Hackers attack pre-paid GSM connections”. 

SIM (Subscriber Identification Module or Subscriber Identity Module) is a specific type of smart card for GSM systems holding the subscriber’s ID number and other information & settings, thus allowing him/her to call from any GSM device. In essence, it is the subscriber’s authorization to use the network. SIM is also supposed to provide location security and call content confidentiality (encrypting traffic between handset and base station). The SIM has these 3 numbers: