At the end Walter, the host, turned to Jimmy, the guest, in the improvised studio office and asked for a reaction. He had liked it, Jimmy said. You didn't get questions like that at press conferences. Depending on how the American people responded, he just might want to do it again.

Of course he will. Politicians often cite the agonies of their profession by saying they are trapped in "no-win" situations. For the President, yesterday's "Call Carter" radio experiment was a "no-lose" situation from the begining. There was no way it could turn out to be anything but a political plus, as it did.

For two hours he answered questions - well, most of them were questions, and some were speeches - from 42 persons throughout the nation. Most of the callers were informed, the questions ranged over a wide spectrum of national concerns, and Carter was relaxed and engaging in fielding them.

With Walter Cronkite, that familiar face, as impresario, Carter and his callers struck up a series of often homey exchanges. They talked, at times, about relatives and visits to their hometowns - or, at one point, of coming to Washington and playing with Amy. It was Hi Jerry, and Cheryl, and Phyllis, and Paul, and John, from the President to the people.And it was Hello, Mr. President, thanks so much and other words of praise from the people.

It was folksy to a fault. But there was no doubt, listening to those voces, that the callers were grateful for the chance to speak directly to their President. And that was the idea. That, and the opportunity for the President to explain his case and boost his public stock.

"I'm rather amazed to be able to get hold of you," said one man from Spring Valley, N.Y., when his call was put through to the Oval Office. His was one of 216 calls that got switched into the White House. One out of five was connected to Carter.

Yesterday's broadcast was, as Cronkite pointed out in the beginning, "unique." If the people didn't get the point, Cronkite hammered it in: it was "indeed historic." A President never had done anything like that before. Carter immediately came on with more of the same: it was a chance to let the people have direct access to him, and for him to learn something of what's of interest to them.

In fact, Presidents are alwas trying new ways to reach wider numbers of people in the most advantageous seting. Recent presidential history is replete with examples of increasing manipulation of the media, particularly through the nation's air waves, to gain support for executive actions.

What made the "Call Carter" broadcast interesting as a symbol of the times was not so much its newness but its reaching back into an older, less-frantic day. Cronkite's initial words over CBS radio stations sounded like a parody of the old, "Here we are, boradcasting from beautiful downtown Burbank." Here they were, Walter advised, sitting in two wing-back chairs, beside a coffee table, before a fireplace, looking out on the beautiful rose garden.

This wasn't a fake, or a setup, Cronkite said, in essence. There was no censorship. But the parttern of some of the calls did raise a few immediate questions. Three of the 42 callers thanked Carter for personally inviting them to his inauguration. Choice or coincidence? Two of the callers came from one place - Lanham, Md.

The last caller turned out to be different from all the rest. She was Michelle Stanley from North Benton, Ohio. Her age, Cronkite told the President, was 11. All the other callers had siad hello or hi to "Mr. President," employing the formal title. Not Michelle.

"Jimmy," she came on, immediately. And then she thanked Carter for inviting her "to your inauguration."

Choice or coincidence?

The caller immediately before Michelle had been from Fayetteville, N.C., giving Carter a chance to say: "My sister lives in Fayetteville, as you may well know."

Perhaps that was just a coincidental selection, too.

But cynicism aside, yesterday's broadcast did have its enlightening moments.

The most arresting exchange came in the fifth call. Nick Kniska of Lanham wanted to know how come Carter's family, including son Chip, Chip's wife and baby, were all living at the White House on taxpayers' money?

Acutally, they weren't mooching off the taxpayers, Carter replied. A President pays all the personal White House expenses out of his own pocket.

That wasn't all from Nick Kniska.How come the new grandchild was born at Bethesda Naval Hospital, a U.S. facility, paid by U.S. funds? There, too, the President explained the situation: a chief executive and his family do have the services of White House physician, and are entitled to be treated at public expense.

Those were questions that had not been raised by the supposed pros - the pres - at his two conferences.

Other callers adked equally serious questions. When he had an answer, as was the case in most instances, the President gave his response. When he didn't know, he said so, and promised a reply by no later than next week.

It was all done with good humor and grace. As is almost always the case, such affairs don't make what the press calls "hard news." The news is in the President's performance and how he is perceived by the public.

By that basis, yesterday's talk-in, call-in or whatever you want to term it was a personal success for Jimmy Carter. Not surprisingly. Walter Cronkite thought so too. Television's most authoritative presence pronounced his personal blessing, and gave his benefiction.

"We'll be glad to sign you up again, Mr. President," said Walter to Jimmy.

"Good deal," said Jimmy to Walter.

And that's the way it was, talk show fans.