Ma Bell loves Uncle Sam. So does the General Telephone and Electronics Company, Continental, Piedmont and nearly 1,000 independent local telephone companies in the nation. For good reason: Uncle Sam talks up a storm, running up an annual telephone tab in excess of $1 billion. And his checks never bounce.

A big chunk of that telephone bill comes from long-distance calls. The U.S. government must be the world's champion long-distance dialer. And Washington, D.C., by any standards, is the world's gabbiest city.

This year, government agencies will make more than 230 million long-distance calls on their private lines. That is enough to make a station-to-station call to nearly every man, woman and child in the country. And an average of 88 calls apiece for each person working for the government. And, like so many government estimates, that one is actually low.

In Washington, federal agencies will make and about 41 million long-distance calls this year, most of them during daylight hours. This is one reason telephone companies give customers a night-time rate. And those figures for government do not include all calls made by the Defense Department, or supersecret agencies that have their own ways. Nor does the figure of 230 million long-distance calls include commercial city-to-city placed from government offices outside the Federal Telecommunication System (FTS).

FTS is the government's private line. It enables federal workers to dial government offices almost anywhere in the nation, or by using area coeds, to reach almost any private or commercial telephone in the country.

Despite Uncle Sam's growing telephone bill, federal officials believe it is a bargain. Especially in these days when non-VIPs are told to travel so much, and people are urged to call an office rather than ring up the motor pool for a car and driver. To borrow from the telephone company slogan, the idea is to let your fingers do the walking.

The government pays about half the commercial rate for long-distance calls made over the FTS. Officials estimate that the average long-distance cost to government during this fiscal year will be 91 cents a call, compared with a commercial average of $1.85.

So the next time somebody in a government agency gives you a don't-call-us-we'll-call-you line, believe it.

Somebody is getting a lot of calls.