IF, God forbid, you are in a disaster situation and are separated from your children, what do you want them to remember? Be sure they know your cell number and the FULL name and phone number of a close friend or family member who does not live in your town!!
Not only should you have them commit the numbers to memory by repeating them to you, have them place calls to these numbers, on a regular basis, so they are familiar with the voices on the phone.