Please keep in mind that The T-Lock Call Blocker is not be able to display phone numbers that your phone service does not recognize as having the correct Caller ID format (e.g. valid name and phone number information).   This is very common with pure voice services from carriers such as AT&T, Verizon, and Comcast.  There is nothing you can do about this.  In most cases, you will not be able to Blacklist these numbers with this device, but you can add the phone number(s) manually by following the steps in Section 4.0 of the manual.