 Nowadays, you can't necessarily believe it all the time because it's so easy for someone to make... By having an audio snippet of your nephew's voice, it could be easy to make them say whatever it is that they want to say. So that's why it's important to be able to vet that person, whether it's by using a code word or asking them a bunch of questions that only that individual would actually know in order to verify and make sure that they're real.