WHILE THE POLICE must get judicial approval before they can eavesdrop on your conversations over the telephone, they can record all the numbers you dial anytime they want to. That's what the Supreme Court said the other day, the explanation being that you have to tell the telephone company what number you want so it can complete the call, but you don't have to tell it what you want to say. By "voluntarily" dialing a number, the court said, you assume the risk that the telephone company will tell the police - or someone else - whom you have called.

When operators handled every call, such a decision might not have seemed so strange. In an era of direct dialing, the idea that the numbers you call are not private is out of place, even though it is clear that the telephone company records some of them - long distance calls, for example - for billing purposes.

Justice Potter Stewart had it right in his dissent when he wrote, ". . . I doubt there are any [subscribers] who would be happy to have broadcast to the world list of the local or long distance numbers they have called. This is not because such a list might in some sense be incriminating, but because it easily could reveal the identities of the persons and the places called, and thus reveal the most intimate details of a person life."

Unfortunately, however, the court's majority believes a "legitimate expectation" of privacy does not exist in information anyone provides voluntarily to others - such as, for instance, the financial data submitted to obtain a loan. This attitude makes it urgent that Congress legislate the kind of protection for individual privacy the justices cannot find to exist in the Constitution. The vehicles for doing this are the proposals President Carter sent to Capitol Hill in April. They should get high priority for final action this year.