This story is just another one of the typical misinformation from the media items. There is no possible way to tell from cell pings that someone "went into the woods for a few minutes"! That is ridiculous speculation. In the Kelsey Smith case, the pings from incoming calls narrowed down her movements to a cell tower along a highway and near a lake area. However, they still did not KNOW she was at the lake area, only that the phone had pinged off of that tower.
The information from the news source states that they have maps of towers near the Anthony home, not maps of where her cell phone actually was at any time. I heard a cell phone "expert" once say that in an area with multiple towers, any one call might switch between those towers several times during a single call. I am not an expert on this by any means, but I am sure that a call from my cell phone could not be exactly located as coming from inside my house, the golf course behind my house or the street in front of the house.