I was under the impression you sell your debt to the collection company and then its no longer your issue. They are responsible for collecting the debt and I am pretty sure that after what they consider "a reasonable amount of time" to repay, which is about 4-6 weeks but varies by company, they then slap a collections notice on your credit file which stays for 7 years and start adding interest as a penalty. I would imagine they buy the debt off you at a certain percent less so they can make money on it.