It is the same number forever. I have numbers for my wife, her mom, her sister, her friend in GuangZhou, etc. When you call them, it assigns a number for you too so that they can call you cheaply. It is a collect call where you pay the $0.019 and they get to call you for free. I highly recommend this service. I use it 3-4 times a week to call my wife and used it 2 times a day in the 2 weeks before her interview to make sure she was completely prepared.