Has the owner of the cell number you’re about to call changed? As a call center manager of permission-based communications, you can’t be entirely sure! About 25% of cell phone owners located in densely populated areas change their number each year. About a quarter of CFPB debt collector consumer complaints are for “no debt owed,” and most of those seem to be to the wrong party. And the FCC’s Declaratory Ruling of July 10th, 2015 confirmed: If a phone number has been reassigned, companies must stop calling the number after one attempt.