Hubby works as a tech for AT&T. As others have mentioned, you could be tracked via triangulation. He says that as long as you were in range of 3 towers to triangulate your position (which you would almost have to be out in the middle of the desert not to be within range <g> or a very, very rural area) you can be located. If there is a lock, it is very accurate, it would be within just a few blocks of your location.
And yes, most newer phones have GPS in them as well.
And like Marcus said - it doesn't matter that the phone call is only 5 seconds long - if there is a connection, there is a record of the call (and what towers the phone was in range of) and can be located from that record.
Hope that helps!
-- DJ
