Somewhere in the White House, a secretary to the vice president sits alone, taking all incoming phone calls.

And in China, Vice President Walter Mondale is on a train, heading from Canton to Hong Kong.

So who is running the vice president's office on a summer's afternoon when everyone is away?

Nineteen phone calls to six offices yesterday elicited this clear answer: Michael Berman . . . sort of.

Berman is the vice president's counsel and legal assistant. He's the man in charge at the vice president's office when Mondale is out of town. Yesterday there was only one hitch -- Berman was also out of town . . . sort of.

The vice president has four offices -- one in the White House, one in the Executive Office Building, one in the Capitol and one in the Dirksen Senate Office Building. This is the chronology of how a reporter attempted to find out who was left in charge yesterday:

3:30 p.m. -- A call to the Capitol switchboard, asking to speak to the vice president. A secretary answers: "Vice President Mondale's office."

After the two agreed that he was out of the country, the reporter asked the secretary who filled in for Mondale in his absence. "Nobody fills in for him, really," she said. "He's always in charge."

The reporter asked the secretary's name, was put on "hold," and was transferred to the vice president's press office.

Ann Stock the press officer in charge, answered. She said Michael Berman was the head person in Mondale's absence. Asked where Berman is now, she said:

"I really don't think he'd want me to tell you." Asked why, she said: "He's taking three days off . . . You can't call him . . . I'd have to reach him with a beeper and ask him if he'd call the Post."

Asked again where Berman is, she said: "I'd really rather not tell you."

3:40 p.m. -- A call to Berman's office. After the reporter identifies himself, the call is transferred back to the press office. Ann Stock again. Nothing new, she says:

3:45 p.m. -- A call to Mondale's office in the Dirksen Building is answered by secretary Liz Brooks. She says Michael Berman is in charge. Asked what she would do if someone had to speak to the person in charge, she said: "I don't know.What do I know? . . . If the vice president was out, I'd call Michael Berman. And in his absence . . . I don't know."

3:55 p.m. -- A call to Mondale's office in the Capitol. The secretary says that in Berman's absence, Bill Smith is in charge. But Smith is on vacation today. She is asked her name. No answer. A click. Then someone else answers saying: "Press office."

Hi, Ann.

4 p.m. -- A call to the Executive Office Building. A secretary says that Berman is in charge, but "Mr. Berman is in a meeting right now." Asked her name, she said, "Hold on a second." Click, click. Back to the press office . . . Well, Ann, just trying to reach whoever is in charge here . . . Talk to you later . . .

Five more calls to the EOB (456-7045). They are all answered directly by the press office.

How did you manage that, Ann?

"I don't know. The phone just rang here," she said.

4:10 p.m. -- A call to the vice president's office in the White House. A secretary (who later is identified as Donna -- she's really very friendly) answers. First time around, she saysBerman is in charge, but transfers the call to the press office when asked her name.

(The reporter has only one question. How come nobody ever tells him they are transferring him to press office? Why is it: "Hold on a second . . . " and that's the end of the conversation?)

Hi, Ann. Call you back later.

Five more calls to the White House Transferred back to the press office each time -- "Could you hold on, I've got another call," the secretary says.

But then someone tells the reporter the secretary's name is Donna. On the sixth call, the reporter asks to speak to Donna.

Donna says she really would like to help, but all questions from the press must go to the press office. Besides, she doesn't know the answer to the question.

"I'm really sorry," Donna says. "I'd like to help, but I'm all by myself here, and I have to answer another call, I have to go."

4:20 p.m. -- This time reporter calls the press office intentionally. Sorry to keep bothering you like this, Ann. Just one question: Is Berman out of town or is he in a meeting?

"I haven't been able to reach Michael yet," she says. "If it's urgent, if the world were coming to an end, he probably would call you. But the world isn't coming to an end, so he probably won't call you . . . You're going to use that quote, aren't you?"

One more time: Who is in charge in Berman's absence? (The tone throughout is humorous, of course).

"Nobody, because Berman is in charge."

But he's not reachable.

"He is in charge."

4:30 p.m. -- The reporter gets a call. It's Chuck Campion, special assistant to the vice president, and second to Berman. He say Berman is out of town . . . though he could be in a meeting . . . somewhere . . .

Where is he?

"He's on . . . I'm not really sure," Campion says. However, he says he has spoken to Berman five or six times already today, and could reach him if he had to.

So, where is he?

"I really don't know where. That's his personal business . . . I'm not sure."

Well, who would know?

"The office manager . . . Susan Holloway."

Where is she?

"She's in China. On the trip."

Does that mean no one knows where Berman is? Is he on vacation, or what?

"He's my superior . . . I can't say where he is . . . I just really don't know whether he's on vacation or whether he's doing office business."

Come on, where is he?

"I think he's in the New York area, I think. I'm really not sure."

By now the office is closed for the Labor Day weekend, Chuck says. But don't worry, the vice president's office is in good hands.

"Every office is taken care of," he says.