Slightly different, but:
When I was in college, somehow one of the Indian students stumbled onto the fact that the phone company apparently screwed up the programming on one of the public phones in the basement of the library so that they could call anywhere for any length of time without paying. Gawd knows who they thought they were billing, but it was a public (coin op) phone. So word spread among the foreign student population and some days there was an hour wait for free calls home to wherever. After about 6 months someone at the phone company evidently realized they made a mistake and fixed it. From what I understand, that phone was listed as a prison phone for a while.