You just think logically. If somebody calls from their cell phone and says that their battery died the last battery you would think of would be their cell phone since they're using it to call you.

So, how did she call you on a dead cell phone battery?

I assumed she was talking about her fantasy league pitcher and catcher.

LOL Less than a minute later, the call was cut off.

Cell phones typically have a battery power meter on the display. Anyone who pays attention to their phone has plenty of warning, and if not they give you a warning shortly before they run out.

Cell phones are communicating with the network even when "hung up" and thus consuming power when you don't expect it.

One cellular company I worked for had a site right on the building. Our office was right on a sector node line, and being as the technology was GSM, there was a spot in the office where you could set your phone and it would do a hard handover every cycle. Battery charge didn't last long.

Another time I was working on a CDMA launch and we were doing continuous cluster map drives. Someone screwed up and got us trickle chargers to run off the inverter. I had two phones rigged to the laptop, one doing short calls and one keeping a long call up. The short call phone could grab enough power during the 15 second pause between calls to hold a charge for an hour. We had to stop for 15 mnutes after each file to cool, swap and charge the batteries.