Smith's 61-year-old mother, Linda Doyle, was T-boned by a 20-year-old driver in Oklahoma City who allegedly ran a red light. He told police he never saw what color the light was, because he was talking on his cell phone and wasn't paying attention.
Doyle died from blunt force trauma to the head, neck and chest.
"I call it 'death by cell phone,'" Smith said.
Since her mother's death in September 2008, Smith has tirelessly campaigned in Texas and Oklahoma for a statewide ban of cell phone use while driving.
"I would like to see the cell phone companies provide better safety warnings like cigarette warnings or warnings on alcohol bottles: 'driving while using this impairs you,'" Smith said.
She said hands-free devices only provide a false sense of security.
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"I learned that it's a distraction in your brain processing -- that you can't, you think you are fine driving and talking, but your brain goes someplace else," Smith said.
A Carnegie Melon University study found that using hands-free devices while driving is still a significant distraction. Drivers who use them commit the same driving mistakes that drunken drivers do, according to the study.
"How important is that call?" Smith said.
Her mother is the face of 180 "Death By Cell Phone" billboards placed around the country by the National Safety Council.
Smith she hopes her mother's story will compel people to hang up before driving.