The SIM card on a smartphone is used to save information such as phone contacts, text messages, voice mail, and details of the last call placed and received. Editing the information on the SIM card keeps the information current and also acts as a backup. If the smartphone is ever damaged, the information on the SIM card can be restored on another device.
Select the contact to edit by going into the contact list of the device.
Click or tap on "edit contact" and enter the necessary changes.
Press the menu key and select save to save the updated information.