Changing the pin code of your phone SIM card is easy, and doing so can help protect your valuable personal data.
In an Android smartphone, go to the Settings menu, select Security, and then tap the "Set up SIM card lock" option. Input the current pin number, and type in the new pin twice.
Menu options can vary slightly for different devices, reports the German publication PC Magazin.
Meanwhile, iPhone users can change their SIM pin by going to Settings > Cellular Data, and most Microsoft phones have the option in the Network and Wireless settings.