In most cases, when changing your SIM, you will lose any voice messages that were saved on the network, and will need to reconfigure your voicemail settings after the change has completed.
Transfer your phone number to a new SIM card. Upon success, place your replacement SIM into the back of your phone and turn it on.
The ICCID is a 19 digit number on the back of your SIM card, marked by the arrows in the image above.