There are several reasons why you might want to track a cell phone. You may want to keep track of your kids for their own safety. You may want to track your phone if it should be stolen. Or you may have some nefarious reason for tracking someone using his or her phone. Whatever your reason, there are several options now available for tracking a cell phone.
You get the number off your caller ID and call them back only to get silence.
It is possible to not only get their name and address but you can look up their criminal and court records, job history, address history, marriage/divorce records and much more.
In almost every case this will immediately stop the harassing text or phone messages.
If you do a search you will find a lot of free services.
If you want the good info, or need to trace a cell number you are going to have to pay a small fee.