Subscriber identity module cards are smart memory cards used by GSM or CDMA cellular phones to store user identity, network authentication, personal security information, text messages and contact phone numbers and email addresses. SIM cards can be read by other compatible cell phones and smart card readers using special software. In order to read a locked SIM card, you should call your cellular carrier to get the personal identification number or PIN unlock key associated with your SIM card. You can then make backups of or modify your contact and text messages on the SIM card. Tips Writer Bio
