If I block a text, will the blocked number know that they are blocked? Call Detector Support - September 12, 2015 14:29 The blocked number does not receive any notification that they were blocked. Related FAQs: How do I block texts with Call Detector? Why is Call Detector not blocking text or SMS messages? Can I view my blocked text messages? What if the number I want blocked isn't 10 digits in length? How do I unblock a number with Call Detector?