Since she's on the phone so much, he thought this would be the perfect proposal. Also, hearing her voice everyday answering the phones is one of the reasons he fell in love with her. He tells her he has to run some errands, and goes to set everything up. Then he heads for the bathroom, but instead takes the back stairs to the roof. He then calls the office phone.
"Dunder Mifflin, this is Pam." "Dunder Mifflin this is Jim." She smiles when she hears his voice. "Hey. Where are you? I thought you went to the bathroom. Please don't tell me you're calling from the bathroom to listen to something Dwight's doing." He smiles, "No, sorry to crush your dreams Beesly. I was wondering if you could sneak out and meet me on the roof?" "Why? Is Michael planning on jumping again?" He laughs. "Unfortunately, no. So, can you come?" "Sure, let me just forward the phones."
She hangs up and smiles to herself. This is probably it, this could be his proposal. She heads out the door and up onto the roof. Once she reaches the top she gasps. Jim has a picnic blanket with rose petals around it and candles lit. He motions for her to come over. She walks over and sits down on the blanket with him.
"It seems like you forgot to bring something to eat. But, lucky for you, I'm a nice guy and will share some of mine with you." he says. She smiles and thanks him as he hands her a ham and cheese sandwich. She thinks back to the first day that Jim was in the office. He was so nervous and concerned, that he forgot to pack a lunch. So, she decided to give him some of hers, a ham and cheese sandwich. He's eaten them for lunch everyday since then. She still doesn't know if he really likes it, or just eats it because of her. That's one of the things she loves about him. The little things he notices about her and how much he cares.
Once they finish their dinner, they stand to watch the sun almost finish setting. He turns to her and looks into her eyes. This is it, she's sure of it. "Hey Pam?" "Yeah?" "You want to know the first time I knew I was in love with you?" She smiles, "When?" "The first time I heard this:" he brings out a tape recorder and hits play. She hears her own voice say, "Dunder Mifflin, this is Pam." She smiles, they both fell in love at first sight even though they originally denied it.
"Pam, I want to hear your voice for the rest of my life. I want to be able to tell people, 'That women answering the phones is my wife.'" She gasps. This is it. Jim gets down on one knee. "Pamela Morgan Beesly, will you marry me?" He opens a box and she sees a simple yet beautiful ring. It's perfect for her, he has such good taste when it comes to getting things for her. She looks down at him and sees him looking at her nervously, she can't believe that he thinks she wouldn't say yes. "Yes!" They both burst into huge smiles as Jim stands up and hugs her. He then gives her a passionate kiss and puts the ring on her finger. "You were right Halpert, that proposal kicked my butt," she says. He smiles and looks down at her. "Thanks future Halpert." They stand there just smiling at each other.