@ElizaBennett - Everything you said is true but I think you left out the most important part of debt collection law - if you ask them in writing to stop contacting you, they have to comply. It doesn't mean that you don't owe the money, just that they can't keep calling you for it. You can also ask them not to call you at work. We went through this with an employee at my old job who was out on maternity leave. Creditors would call looking for her and we kept referring them to HR, but the calls kept coming until we started sending them written notices. (It was a pain, but worthwhile for the receptionist.)
And remember that debts disappear off your credit report seven years after the last activity. If the debt is, say, six and a half years old, your credit score might actually be better served by ducking their calls and waiting it out rather than by making a payment, which moves that bad debt right to the top again. They can try to collect debts that old but they just don't have much of a leg to stand on.