Boost Mobile makes it easy for their customers to block calls. Follow these simple steps to manually add a number to the block list on your Boost Mobile phone. The first thing you want to do is click on the Manage icon in your Boost Mobile phone app and select Block. Next, select the + button on the bottom right-hand corner and enter the 10-digit phone number into the search box. Once the number is entered, select Search to add that number to your block list.