Every cell phone on a Global System for Mobile Communications (GSM) network utilises an International Mobile Subscriber Identity (IMSI). The IMSI, located inside your SIM card, stores all of your cell phone's information. IMSI catchers steal your cell phone's IMSI information to record your phone calls. These devices, illegal in many areas, pose a threat to your personal privacy and security. Though there is no one method to disable IMSI catchers, you can take measures to prevent IMSI catchers from stealing your information.
Search your home or office. Look for new objects or objects that you do not recognise. If you find an unusual object, look for its "On/Off" switch. Turn the switch to "Off." If possible, remove the object from your home or office.
Upgrade to a 3G only cell phone. Many IMSI catchers force cell phones to use their 2G frequency. If your phone cannot use 2G, IMSI catchers cannot steal its information.
Switch to a cell phone network that does not use a GSM network. IMSI catchers steal information from GSM networks but cannot steal information from other types of connections. In the United States, T-Mobile and AT&T use a GSM network. Sprint and Verizon use CDMA.
Purchase a secure phone, such as a Cryptophone. These phones use encrypted connections to provide extra security. However, they typically fail to offer the options of other phone networks.
Use your cell phone's data connection to make calls. Visit a Web-based calling website, such as Skype or GoogleVoice. Register for an account and add your friend's phone numbers to your contacts list. Tap a contact to call him.