My dad told me about some scam ( i dont know if its true or not, i have never cared to double check it) that some foreign numbers were calling people in the us and the cost for staying connected was a few thousand dollars a minute. The people in the US don't know this so the guy on the other side would try to keep the line up as long as they could.

Of course this could be complte horseshit, but I'm going by what my dad said.