Legal Question in Personal Injury in California

You would need to personally serve the defendant (give them a copy of the lawsuit), and that presupposes you can identify and locate the defendant. Even if you could identify the telephone subscriber, which is a huge "if," you would need to be able to prove that he or she or it was the person that caused you harm. It's not clear how it would occur that someone whose identity is known only to you by a phone number could cause you legal harm.

If you have no address then you can not serve the Claim and can not get a judgment, so ther is little purpose to pay to file. You can use a reverse phone number directory to find out who that number is listed to.