It started out as a campaign promise by Rep. Thomas A. Daschle in 1978: a toll-free help line. But for scores of his constituents, the South Dakota Democrat's 1-800 number has turned into a life -- and death -- line.

Last week it brought a death notice, the last wish of a Korean War veteran, Larry Rodman, 48, in and out of veterans hospitals most of the time since the war. For him, "next of kin" was the voice at the other end of the telephone: Lee Edel, who has been manning Daschle's 1-800 line from the beginning.

Edel has become the voice of concern here for others in distress, whether they are veterans, parents looking for lost children, needy families, Medicare patients, Social Security recipients or South Dakota's farmers feeling the squeeze of the Reagan administration's farm policies.

Lately, most of the calls for help have come from the farmers, some of them suggesting a solution all too final. "We used to get a suicide call every six months; now it's about once a week," says Edel.

Sometimes the callers are distraught farm wives secretly seeking help for husbands who face foreclosure and bankruptcy. Sometimes they are the farmers themselves, telling their personal versions of the now-familiar Farm Belt horror stories about sheriff's sales and auctioneers.

Edel says she does not panic at talk of suicide. "Having had two parents who went that route, I am not easily shocked," she says. Instead, she listens, using a calm, sympathetic, if reasoned, approach in telling the caller "what it's like for those they will leave behind."

Larry Rodman's first call in 1982 also had that desperation in it. He telephoned from a South Dakota veterans hospital seeking help for his tangled affairs as a war veteran. In the years that followed (and in accordance with instructions from Daschle, a member of the Veterans' Affairs Committee, to take calls from veterans wherever they are), Edel and Rodman continued to talk, wherever he went -- the Midwest, New England or the South. If she took a special interest, she says now, it was because she discovered early that his home town, too, was Canton, Ohio.

Then last week a woman called from the veterans hospital at Johnson City, Tenn., to tell Edel that Rodman had died of heart complications. Following Rodman's instructions of whom to notify in case of death -- "Lee-1-800-424-9094" -- the astonished hospital worker told Edel, "I didn't think you existed."

When Edel hung up, she made her own phone call. Yes, the florist said, he would see to it that a single red rose was placed on Larry Rodman's grave.

Look for Nancy Reagan to visit Malaysia as well as Thailand when she accompanies President Reagan to the Western Economic Summit in Tokyo this spring. Since she's going to be looking at narcotics problems, drug users may well hope she doesn't come home with any ideas.

They hang drug traffickers in Malaysia. The country has some of the world's toughest antinarcotics laws, including a mandatory penalty of death by hanging for anyone found in possession of more than 15 grams (about half an ounce) of heroin or 200 grams (about seven ounces) of marijuana or hashish. Since 1975, 31 persons have been executed there for drug offenses, and 60 others are on death row pending appeals.

Mrs. Reagan's advance team, including new chief of staff Jack L. Courtemanche, met with her yesterday for the first time after returning from a 10-day trip to Southeast Asia. Her office said an announcement on her itinerary will be made later.

As most of Washington's lawmakers can verify, when the president has a point to make he's likely to pick up the phone. So last week, he must have said something like, "Hello, Central, get me Morocco."

He was tracking down his man on the move, the United States Information Agency's globe-trotting director, Charles Z. Wick, who was in Morocco for the bash King Hassan threw on the 28th anniversary of his ascension to the throne.

Called to the phone at the palace, Wick told Reagan that he caught him on his way into dinner with Hassan, Spain's King Juan Carlos and the former king Simeon of Bulgaria.

History does not record whether the leader of the free world apologized.

Other outgoing and incoming White House calls:

*President Reagan's, personally pledging $1,000 to the Easter Seal telethon when he returned from Camp David Sunday night. Because he called between 8 and 9 p.m., the president will receive a $5 gift certificate from Safeway. When she heard the news yesterday, Elaine Crispen, Mrs. Reagan's press secretary, asked, "You mean we can use it when we take Mrs. Gorbachev to the Safeway?" [Raisa Gorbachev is expected to accompany her husband to the next U.S.-Soviet summit in Washington.]

*Nancy Reagan's extending good wishes to the mothers of Troy Grant, 3, and Carlos Cyris, 6, as they prepared to fly home to Grenada over the weekend. Both youngsters had undergone heart surgery at the Deborah Heart and Lung Center in Browns Mills, N.J., as part of a program that brings children to the United States for medical treatment. Troy and Carlos, with their mothers, had come to the United States on the back-up plane accompanying President Reagan home from his trip to Grenada.

*Tessa Taylor Tobias' call to Nancy Reagan about the death from cancer of her stepfather, the film industry's Marshal Shacker. Shacker married Tobias' mother, Ursula, the widow of actor Robert Taylor, 13 years ago. Tessa Tobias is goddaughter of Nancy Reagan, who keeps a photograph of her in her wedding gown in her White House bedroom. The Reagan-Taylor ties don't end there. First Son Ronald Prescott Reagan is Ursula Shacker's godson, as he also was the late Taylor's.

Even the Soviet Embassy is gearing up for what promises to be the farewell party of the year -- if not the decade. "That's what the protocol people tell me," Oleg Sokolov, the embassy's minister counselor, said of speculation that Ambassador Anatoliy Dobrynin's swan song to official Washington after 24 years on the job will be a fete to end them all.

Meanwhile, back from Moscow where he was U.S. ambassador from 1981 to 1986 is Arthur A. Hartman. He'll be honored March 18 at Georgetown University when he receives the eighth annual Jit Trainor Award for Distinction in the Conduct of Diplomacy. The award is named for J. Raymond (Jit) Trainor, registrar of the School of Foreign Service for many years. Alumni set up an endowment in his honor to recognize distinguished service in the diplomacy.