First to Jay. Even though you wrote about Cash Call and this report was mainly about Drive, you did write your comments as a "guaranteed" way to get out of your debt. This is not very wise as there are different situations, and you may cause people more problems. Because what worked for you may not work for others. This is why it is best when dealing with suits it is best to consult a lawyer who can review the specific situation and give you advise based on that.
So in general a couple of comments. First the FDCPA does allow you to send a Cease Communications(not Cease and Desist) Letter to a Collection Agency. Once they receive that, you are correct(and the only thing that I think you got correct), they must not contact you again by phone unless it is to inform you that they will be taking further action. However, Cash Call is considered an Original Creditor so this does not apply. Now, some states such as California has additional laws that cover the Original Creditor.
As for being sued. It depends on the State as to the Small Claims limit, some have limits up to $10,000. But there is nothing that says they can not sue you in a regular court. If they sue, and even if the judge says you only owe the original amount. You are still going to be responsible for the court and attorney fees. This alone could be several hundred dollars. If you do not pay the judgement they may have the right to garnish your wages or attach your bank account. The court may also impose a Post Jugement interest rate on the unpaid balance. This is of course is assuming(and we all know what happens then) that the judge will see it your way. There is NO guarantee of what a judge will do, so it could be quite possible that the judge orders you to pay the entire amount in the original agreement with full interest.
Now to Michael, you are correct in Texas they can not garnish your wages for a "consumer debt". However, they can still attach your bank accounts. If that never happened to you, then you either didn't have enough money for it to be worth their time, or you kept it hidden well enough that they couldn't find it. In addition to attaching your accounts, they may be able to place a lien on any real property you own, such as a house or another car.
Also, in Texas a Judgement is valid for 10 years, and is renewable in most conditions. So it could effectivly be enforceable forever. Just because it is off of your credit report does not mean that it is still not active, and one day you may get a "surprise" when all of your money is gone from your bank account.