The woman, Carla Chapman of Plant City, Florida was working in her backyard when she fell through the surface and into a sinkhole. She had her cell phone on her, but the sinkhole created terrible reception and she kept getting disconnected when she tried calling for help. Finally she got the idea to dial 911 and then throw her phone up out of the hole back into her yard where there would be a cleaner signal.
The gambit worked, the 911 call went through, and a police officer responded to her home, eventually finding Carla trapped in the backyard sinkhole. Additional rescuers were summoned and they worked to get her free.
As an added twist to the story, this wasn't first time Carla got trapped in a sinkhole in her backyard. In 2010 another sinkhole on the same property also tried to swallow her but she was fortunately rescued by a neighbor.
Story sources:
http://www.wtsp.com/news/topstories/article/184072/250/Woman-rescued-after-swallowed-by-sinkhole-
http://www.wtsp.com/news/local/story.aspx?storyid=131394