Frank Sinatra, who has had reason in the past to suspect that the FBI and others might be listening when he and his friends talk on the phone, has reportedly bought three $125,000 portable scrambling devices.

The equipment, outfitted into attache cases, is made by the Gretag company in Zurich, Switzerland.

President Carter has been using a similar American-made scrambler in his limousine -- called a "digital voice privacy system" -- since last year.

Carter's was installed by Motorola and scrambles his conversations on a frequecy that is changed often for security reasons.

Only two people at Motorola know the frequency, a spokesman says, and they will be fired if the frequency gets out, even though would-be eavesdroppers still need a special decoder on the other end.

The sophisticated scrambler was designed by Motorola especially for the government.

Other top officials, including CIA director Stamsfield Turner, also are already using the gadget.

They're not for sale to pimps and prostitutes, who are big customers for Motorola's standard car phones.

How does Motorola KNOW they're pimps and prostitutes, you ask?

"Because they always pay cash," says the spokesman.

Don't get mad, get even.

Reporters traveling with Ronald Reagan in South Carolina last week didn't make much of his accusation that President Carter has failed to control waste and fraud and abuse in federal spending.

The fact sheet for that little-noticed speech came from General Services Administration employes who feel that the Carter administration never got to the bottom of the scandals there.

Reagan has promised them that one of the first things he would do in the White House is reopen the GSA inquires.

He may be too late.

Jay Solomon, the GSA director who resigned in disgust when his cleanup efforts got nowhere, found empty filing drawers on multimillion-dollar projects when he went after evidence in some cases.

As the youthful publisher of Washington's glossy society magazine, "Dossier," David Adler is supposed to be an arbiter of socially acceptable behavior at parties.

So imagine the amazement and amusement when he whips off one of his shoes in public and does an imitation of Maxwell Smart:

"Hello, Chief . . ."

It is his way of poking playful fun at least one of the Intertel agents he has encountered recently after that private intelligence network was hired to investigate the Rev. Sun Myung Moon's Unification Church for The London Daily Mail.

The Moonies are suing The Mail over a story about young Adler's brainwashing experiences with that cult.

If those two button-backed photos of Ronald Reagan had been pinned any lower on each side of her white mink cape, Washington socialite Rose Saul Zalles might have looked more risque than any Republican likes to get.

The badges have poked holes in her fur.

"But it doesn't matter, dear," she said at a party. "If Reagan isn't elected none of us will be able to afford mink anymore anyway."

An "Architectural Digest" interior can raise more money for a political candidate in Washington than live celebrities.

Address-dropping can be valuable to the upwardly mobile, and it's worth a couple of hundred dollars to be able to refer casually to an evening spent at one of Washington's social showplaces as if you dined there regularly.

So the David Lloyd Kreegers' architectural masterpiece by Philip Johnson will be opened for Carter supporters next Thursday night.

And on Tuesday, farther up Foxhall Road, the William McCormick Blairs -- two Teddy Kennedy loyalists who couldn't forget -- are opening the doors of their glorious Billy Baldwin interiors for Rep. John Anderson.