Why would I want to print my phone number on my state return?

neither the IRS nor state would call you first. if there was a problem with your return. the first thing you would receive is a letter/notice.  if you call them they may ask for the phone number on record or use it to call back if disconnected.

Thanks, Mike.  I didn't know whether they'd call with a question.  I'd rather have any correspondence from Fed or State in writing.

Are you good at writing a personal check legibly ?
If so, they won't use the phone number you write on your check.