I've never heard of POP-CORN. Growing up in Louisiana, the time/temp service was always provided by a local bank as a form of advertising. They always had a separate number for it, but it changed from town to town. We called it all the time; particularly after a storm outage, when we wanted to synch our clocks back again.
It makes a fair amount of sense for banks to have done it, seeing how many banks still have time/temp marquees on their buildings. (I still pass two of those on my daily commute.)
PS: Out of curiosity, I decided to see if my city still had a time/temp line, and it does. Just called it to verify. (These days it is sponsored by a law firm.) I also found this 4 yr old newspaper article about how the number of calls to it was declining:
http://newwentzvillian.blogspot.com/2014/07/i-phones-are-killing-st-louis-time-and.html