These days, telephone conversations with George Mason University freshman Bill Rosenberg are likely to be interrupted every few minutes by the click, click of his call-waiting service.

"Right now it's just touch and go," said Rosenberg in a telephone interview interspersed with interruptions from volunteers, suppliers, donors and shopping mall representatives. "Sleep is less of a concern right now than the homeless."

Rosenberg, an 18-year-old T.C. Williams High School graduate, is organizing a project to raise money for homeless people by selling Valentine's Day roses at shopping malls. He is finding that setting up a charitable campaign is not always, well, a bed of roses.

One day last week, he sat down with a florist for three hours to learn how to keep roses fresh and sell them, followed up on his numerous press releases, and arranged television interviews. "It's more difficult than one would imagine," he said.

His efforts began in a freshman economics class after the October stock market crash. "I was analyzing the stocks, and something like a trillion dollars evaporated . . . . I realized there was going to be some serious problems economically, and I wanted to do something to help the homeless."

He decided to sell fruit baskets for Christmas and donate the proceeds to ALIVE, an Alexandria charitable organization set up by 38 churches that operates shelters for the homeless and helps pay rent for Alexandria families facing eviction.

He persuaded about 25 students at his alma mater Hammond Intermediate School in Alexandria to help assemble and sell the baskets, and his father lent him $5,000 for start-up money. But then he had to master the arcana of fruit basket making and marketing.

"I'm learning how the capitalist system works. There's so much that isn't in the textbooks," he said. "Wholesale versus retail, how to write up a form for a shopping mall to release it {from liability for fund raisers} . . . how to use a warehouse, order over the phone . . . follow up on press releases."

Just buying the wicker baskets wholesale was "awful difficult because you don't know where to start" and it requires a wholesaler's license. Many malls turned down his requests for space, telling him that if they let him sell, they would have to let everyone else who asks.

He and the student volunteers set up an assembly line to put the fruit together with baskets, shredded tissue paper, Christmas decorations, cellophane, ribbon and candy.

Rosenberg said they made about 500 baskets, which sold for $15 each. They also collected $500 in donations, he said. After paying expenses of $5,500, $2,500 was left for ALIVE, he said. Rosenberg said all his work for ALIVE is volunteer, and he keeps no money for himself.

Rosenberg almost sounds like the owner of a fresh produce delivery service, which he once was, as he describes his newest project, selling roses. "Nobody's ever sold roses for such a price" at Valentine's Day, he said. Several florists said that prices this year for Valentine's Day will run $50 to $80 a dozen. His will sell for $39.95. "We have no overhead; we use volunteer workers," he said.

Rosenberg estimated that $10 for each dozen roses sold will go to ALIVE. "We've got no limit. As long as we have the check in the P.O. box by Tuesday the ninth, we can handle any amount of orders . . . . If we sell 10,000 {dozen} roses, that's $100,000 for the homeless. If we sell 1,000 {dozen} roses, that's $10,000 for the homeless."

Rosenberg is "a very persistent and aggressive fellow," said Richard Glassco, president of ALIVE. "He's very enterprising in running this business; he's learning a lot about getting permission from places to do this . . . . It's been very surprising how much he's been able to do, how far he's gone."

Rosenberg has aggressively sought media attention for his campaign, and WTTG-TV (Channel 5) and WUSA-TV (Channel 9) have done news segments on it. He says he expects to wait until a luncheon he plans for the end of February to turn over all the money he has raised since December to ALIVE because "we wanted to make it real newsworthy."

He says that he has not had time for detailed record keeping and that his receipts are "in a box."

"I'm just a college student trying to raise money for the homeless," he said.

Rosenberg has established an information number for buyers, 823-ROSE.