What is the reason contract phones cannot be used on a prepaid plan?

[jdh-ohio]

I originally posted this question in the Basic Phones forum, but I think that may have been the wrong place to ask this.

I am interested in activating a phone on the $50 basic phone prepaid plan, but the phone I tried to activate would not work.  It was the Casio Ravine 2 C781.

I already know that contract phones will not work on the prepaid plan.  I also have already spoken with two customer service reps, and they were helpful, but they could not answer my questions.

What is the actual reason that basic feature contract phones will not work on the prepaid basic plan?  Is it the PTT feature?

The Ravine 2 was new with a clean ESN, and it's just a basic phone.  I don't blame anyone except myself, but I would like to avoid this in the future. btw, I gave the Ravine to my mom and dad who are on a contract plan, and it is working great.

One of the reps I spoke with said that this may change in the near future, and that phones like the Ravine 2 may work on the prepaid plan soon.  Does anyone know if this is true?

To make things more confusing, I just read an older post that states if a contract phone like the Ravine is activated for at least 6 months, it then can be activated on a prepaid plan.  Is there any truth to this?

Finally, I understand that there are some basic flip phones available that I can purchase like the Revere 2 and the Gusto 2, but I prefer the quality of the Ravine 2.  I need the rugged phone capability due to my work environment.

Thanks for your time.

Jim