Moments before United Airlines Flight 175 smashed into the World Trade Center on September 11, 2001, a passenger left a voicemail for the wife he'd left behind in Massachusetts.
"Jules, this is Brian. Listen, I'm on an airplane that's been hijacked," said Brian Sweeney, a 38-year-old aeronautics consultant and former Navy pilot. "If things don't go well, and it's not looking good, I just want you to know that I absolutely love you.
"I want you to do good, go have good times — same to my parents and everybody — and I just totally love you … and I'll see you when you get there.
"Bye babe. I hope I call you."
Mr Sweeney called his mother to say he loved her, and tell her the passengers were planning to fight back. "They might come back here," he said. "I might have to go. We are going to try to do something about this."
Three minutes later, the plane crashed into the top floors of the South Tower.
The voicemail is one of heart-wrenching final messages that visitors to New York's 9/11 museum can listen to through telephones fixed to the walls.
They are the last words of passengers, crew members and office workers who were among the 2996 killed when terrorists hijacked planes and crashed them into the Twin Towers, the Pentagon and a field in Pennsylvania.
Their voices convey both the primal fear of the moment they realised they are likely to die, as well as a need to reassure and comfort loved ones.
They are perhaps the saddest recordings you will ever hear.
MELISSA DOI was a Northwestern University graduate who dreamed of becoming a ballerina, and worked as a manager at IQ Financial Systems. She called 911 from the 83rd floor of the South Tower, 2 World Trade Center.
Doi: It's very hot, I see … I don't see, I don't see any air any more!
911: OK …
Doi: All I see is smoke.
Doi: OK dear, I'm so sorry, hold on for a sec, stay calm with me, stay calm, listen, listen, the call is in, I'm documenting, hold on one second please …
Doi: I'm going to die, aren't I?
911: No, no, no, no, no, no, no, say your — ma'am, say your prayers.
Doi: I'm going to die.
911: You gotta think positive, because you gotta help each other get off the floor.
Doi: I'm going to die.
911: Now look, stay calm, stay calm, stay calm, stay calm.
Doi: Please God …
KEVIN COSGROVE was on 105th floor of the same building when he called emergency services from an office at 9.54am. The 46-year-old father of three was trapped in an office with co-worker Doug Cherry, trying to breathe through thick, black smoke.
Cosgrove: Lady, there's two of us in this office. We're not ready to die but it's getting bad.
911: We're getting there.
Cosgrove: Doesn't feel like it man, I got kids.
Cosgrove: There's smoke really bad.
911: Sit tight and we'll get to you as soon as we can.
Cosgrove: I know you've got a lot in the building but we're up on the top. Smoke rises too. Come on, I can barely breathe now — can't see. It's really bad, it's black, it's arid. We're young men, not ready to die.
911: Hello?
Cosgrove: Hello … there's three of us, two broken windows … Oh God — oh!
His phone call ends abruptly, with screams and the sound of debris falling as the call cuts off.
MELISSA HARRINGTON HUGHES was only in New York for one day on business. She called her husband Sean in San Francisco.
"I just wanted to let you know I love you and I'm stuck in this building in New York," she said in her voicemail.
"There's lots of smoke and I just wanted you to know that I love you always."
CEECEE LYLES was a flight attendants working on board United Airlines Flight 93. When the plane was hijacked on September 11, the mother-of-four called home twice, but could not reach her police officer husband, who was sleeping after a night shift.
United 93 was the plane on which passengers and crew decided to fight the hijackers, and it was during the clash that it crashed in Pennsylvania, just 200 kilometres northwest of Washington, DC.
It's believed they prevented an even worse tragedy, and many more lives being lost.
"Hi baby," Ms Lyles said in her voicemail. "I'm — baby, you have to listen to me carefully. I'm on a plane that's been hijacked. I'm on the plane, I'm calling from the plane.
"I want to tell you that I love you. Please tell my children that I love them very much. And I'm so sorry baby.
"I don't know what to say. There's three guys, they've hijacked the plane … we're turned around and I heard that there's planes that have been flown into the World Trade Center.
"I hope to see your face again, baby. I love you.
"Bye."
BETTY ONG was a flight attendant on American Airlines Flight 11 from Boston to Los Angeles, the first plane to be hijacked. She phoned American Airlines reservations and Nydia Gonzalez, an operations agent, using a seat back Airfone at the back of the plane. These are extracts of the conversation.
Ong: The cockpit's not answering. Somebody's stabbed in business class, and um, I think there is mace that we can't breathe. I don't know, I think we're getting hijacked … my name is Betty Ong. I'm Number 3 on Flight 11.
AAL: Can you describe the person, that you said someone is what in business class?
Ong: I'm — I'm sitting in the back, somebody's coming back from business. If you can hold on for one second, they're coming back. (Inaudible) Anyone know who stabbed who?
Background: I don't know, but Karen and Bobby got stabbed.
Ong: Our — our Number 1 got stabbed. Our purser is stabbed. Ah, nobody knows who stabbed who and we can't even get up to business class right now because nobody can breathe. Our Number 1 is — is stabbed right now. And our Number 5. Our first-class passenger that, first class galley flight attendant and our purser has been stabbed and we can't get to the cockpit, the door won't open. Hello? … Can anybody get up to the cockpit? We can't even get into the cockpit. We don't know who's up there.
AAL: Well if they were shrewd, they would keep the door closed, and —
Ong: I'm sorry?
AAL: Would they not maintain a sterile cockpit?
Ong: I think the guys are up there. They might have gone there — jammed their way up there, or something. Nobody can call the cockpit. We can't even get inside.
(American Airlines relays the information to an emergency line)
AAL: What's going on, Betty? Betty, talk to me. Betty, are you there? Betty? (Inaudible) Do you think we lost her? OK, so we'll like — we'll stay open. We — I think we might have lost her.