My girlfriend's cell rings constantly from NCO, under two separate numbers. 2154368620 and 6512041366. They call anywhere from 5 to 20 times in a single day at all kinds of weird times ranging from 6 AM to midnight. I'm going to start calling them repeatedly and harassing them the way they do us. Every time we answer it's either dead air or some Indian. It's a pre-paid cell phone to boot, so every time we do answer, it's wasting money. They never even tell us what we want, they basically blackmail us with "Ok, we'll tell you who we are, as soon as you give us all of your personal information". No thanks, terrorist.
They call and call. I learned on the internet that this a scam number used by NCO Financial. This is an outfit that buys old, uncollected bills, whether they have been paid makes no difference. They hope to intimidate you into paying them. The people who NCO uses speak very little English so don't say much; they won't understand but you ARE being recorded.