Its a good idea to get one or something like it.  Various companies have different plans.  I decided on a T-mobile phone because it allowed me to get the cheapest price per month which is what I wanted given that I will be using a small amount of minutes.  T-modile also let you register right on-line.

I have a prepaid T Mobile phone from Wal Mart.  The girl in the electronics dept set it up for me right in the store...... all I needed to give her was the zip code. This way it's not traceable to me in any way.  I buy refill cards at Holiday Stations, Target, or Wal Mart and refill minutes from the phone itself.

I've never fully understood how Trac Phones or disposable phones work. When you activate one of these phones you don't give your name so on a caller ID, only your phone number is displayed but not your name. Providers invariably specify that they don't accept blocked calls but apparently a call that only displays the number, not the caller name is OK? I guess I don't understand what sense of security this gives the lady.