John's mom has an iPhone, but he's unable to call her or text her. It goes straight to voicemail. Leo says it's possible that she accidentally blocked John's number because that's exactly the result - it goes straight to voicemail. She may have also turned on do not disturb. Leo says that if she has turned on Do Not Disturb, there is a setting that will ignore DND for your number or other loved ones. So look in the settings. Here's a technote from Verizon on how to find out what numbers are blocked.