How does cellphone tracking work?

well if the phone does not have a gps(say an older phone) then if he is near cell phone towers they can triagulate the signal from his phone even if hes not making a call. they can do this because there is still asignal going to the phone, thats why you still have a signal eve when youre not using it. it might take them a little bit to find him. but if hes moving it would be longer. id say a day or 2 at the most.