If you are like me you hate harassing phone calls from telemarketers. They call and take you away from what you are doing but you try to be nice and tell them you are not interested. Then within a day or two they call again and then again.
Such misuse of the telephone has caused many people, when asked for their phone number, to give a false number. Sometimes they are real numbers just not the number of the person giving out that number. The result of that is someone else gets the call.
You may be wondering what this has to do with ham radio.
When taking a test for ham radio you are asked for your phone number. It is estimated that over half maybe as high as three quarters of the numbers given are incorrect numbers.
These numbers are used by the ARRL to send a message of congratulations to those who successfully pass the test. It is not necessary to enter any number so if you do not want to receive the message of congratulations from the ARRL just leave that space blank. It is just common courtesy.