Los Angeles, California (CNN) -- A paramedic who rushed Michael Jackson to a hospital the day he died said a recording purported to be him calling the emergency room is a fake, according to the Los Angeles Fire Department.
A British tabloid posted the recording online, suggesting it was evidence that Jackson had no pulse at the time, contrary to what his personal doctor said.
The audio "has been determined NOT to be the voice of any member of the Los Angeles Fire Department," fire spokesman Brian Humphrey said in a written statement Wednesday.
"The Firefighter/Paramedic who handled communications for that incident has confirmed to LAFD Administration that the voice is not his," Humphrey said.
One initial cause of skepticism about the recording was that the speakers did not use "standard protocol or established practice" followed by professional paramedics when they communicate with hospital staff, Humphrey said.
Dr. Conrad Murray has been charged with involuntary manslaughter in Jackson's June 25 death, which the coroner ruled was caused by a combination of drugs given to him that morning.
The Sun newspaper did not reveal the source of the recording, but characterized it as a "911 tape."
The disputed recording features a male, who says he is a paramedic in an ambulance, speaking to a female, who is supposedly at the emergency room of UCLA Medical Center.
"We have a male, 50. Pop star Michael Jackson. Unresponsive, no pulse. Tried to resuscitate him. Unsuccessful. We are en route," the male voice said.
"OK. We'll have doctors standing by," the female voice replied.
"We've done everything we can here in the ambulance. Hopefully, when we get there -- we should be there in five minutes," the male said. "It doesn't look good."
Humphrey said it is routine for paramedics to use a cell phone or a two-way radio to talk to an emergency room as they rush to a hospital, but they "don't normally speak like this in a medical response."
Specifically, the paramedic would not be likely to use a patient's name in the conversation, even if it is a celebrity, Humphrey said.
It would be routine for the hospital to record the conversations for legal reasons, he said.
UCLA Medical Center spokesman Dale Triber Tate said, "There is no way we could authenticate it even if we had patient/estate authorization, which we do not have."
An authenticated recording of the 911 call for help from Jackson's Holmby Hills, California, home was released by the fire department the day after the pop icon's death.
A Jackson bodyguard, who was in the room as Murray tried to revive him, spoke to the 911 operator:
"He's not breathing, and we're trying to pump him, but he's not breathing," the bodyguard said. "He's not responding to CPR or anything,"
"We're less than a mile away and we'll be there shortly," the operator said.
Hoax recordings have emerged since Jackson's death, including a video produced by a German TV show that purported to show a living Jackson stepping out of a coroner's van.
A spokeswoman for RTL, the leading private broadcaster in Germany, later said it was an experiment to show how easy it is to spread rumors online.