The dispatcher gave her CPR instructions which she relayed to Murphy's husband, Simon Monjack, who had already started attempts to revive his wife.
On the 911 tape just released Friday. Sharon Murphy tells the dispatcher her daughter passed out and that she been sick with flu-like symptoms the last few days, but she said the actress was not taking any medication at the time.
"My daughter's passed out," Sharon Murphy tells the dispatcher. "Brittany please come back!" she is heard screaming.
She also said on the eight-minute call that no one saw how Murphy collapsed. Sharon Murphy is heard crying and wailing at times on the call.
Murphy moved with her mother, Sharon, to Los Angeles when she was a teenager to pursue an acting career. She started out in sitcoms and commercials in the early 1990s before winning starring roles in several films.
Her breakthrough role came in 1995, as a dowdy high school student (and best friend of star Alicia Silverstone's character) in "Clueless."
Murphy worked steadily after that. She shared the screen with Winona Ryder and Angelina Jolie in 1999's "Girl, Interrupted." She played Eminem's love interest in "8 Mile" and Ashton Kutcher's wife in "Just Married." She starred as a suspicious girlfriend in 2004's "Little Black Book" and a barmaid with an abusive ex-boyfriend in 2005's "Sin City." She also voiced Gloria the penguin in the 2006 animated film "Happy Feet."
The Associated Press contributed to this story.