American Telephone & Telegraph Co., in what would be the biggest stock transfer in U.S. corporate history, yesterday proposed giving its 3.2 million shareholders initial control over the nation's new independent telephone system.

The transfer proposal, which requires federal court approval as part of the company's antitrust settlement with the Justice Department, would give AT&T stockholders one share in each of the seven new regional telephone companies for every 10 shares of AT&T stock they hold.

Investors with fewer than 10 shares would receive cash instead of a stake in the new companies. In either case the investors would keep the same number of AT&T shares that they previously held.

Stockholders with more than 10 shares and less than 500 will be given access to a computerized system of distributing their shares with a set of options. More than 900,000 AT&T shareholders have less than 20 shares.

Almost a year ago, the Bell System signed a historic agreement with the government providing for the spinoff of AT&T's 22 local phone companies in exchange for an end to the antitrust suit.

The stock program was just one part of a 471-page reorganization plan, which updates the corporation's divestiture efforts. It must be approved by U.S. District Court Judge Harold H. Greene, who presided over the antitrust case. Greene will evaluate the plan after the close of a 60-day comment period.

Equally complex are the company's plans to split its assets, equipment and other holdings worth $140 billion to $150 billion. About three quarters of those assets will go to the seven newly established local operating companies, which serve 80 percent of the nation's phones.

In the Washington area, telephone service would be provided by the Mid-Atlantic company, combining the four Chesapeake & Potomac companies with those serving Delaware, New Jersey and Pennsylvania. The new local company will have assets of $17.2 billion and 108,103 employes.

The plan for breaking up the nation's largest company comes as the telephone giant prepares to create a new subsidiary, American Bell Inc., through which it will be free for the first time to sell computer equipment and to market more conventional telephone gear on an unregulated basis. That venture was mandated by a Federal Communications Commission decision. American Bell begins operation Jan. 1.

Beginning on that date, telephone customers no longer will get phones from their local telephone company. The local companies will only supply the telephone line and the jack linking the phone to the nationwide network. American Bell, using more than 500 of AT&T's existing phone center stores, will compete with other equipment manufacturers for telephone sales.

Both the establishment of the separate subsidiary and the divestiture, set to take place Jan. 1, 1984, are steps in a series of revolutionary changes in the structure of the nation's telecommunications industry.

Although there has been considerable acrimony between AT&T and its competitors as the changes moved through the courts, the FCC and Congress, there was little immediate feedback on the AT&T plan from industry spokesmen.

By late yesterday, the filing had not been widely disseminated, although reporters were briefed on its contents and given copies at midday. The Justice Department does not plan to comment until after the 60-day period, a spokesman said.

From securities analysts, who generally have been concerned about the plight of the stock of the widely held company, the reaction was generally positive. In particular, analysts cited the announcements that trading in the stocks of the divested companies would begin before Jan. 1 and that first-quarter-1984 dividends for the newly issued stock would be set late in 1983.

"What's interesting is their concern for the shareholders," said John Bain of Lehman Brothers Kuhn Loeb. "It is a more dramatic plan that I expected and quite an effort."

Edward M. Greenberg of Sanford C. Bernstein & Co. said the fact that the stock would trade on a "when-issued basis" is "very important in terms of valuation . . . . We'll have a sense of the stock's worth before divestiture takes place," Greenberg said.

But key questions have yet to be answered about the effects on AT&T customers.

For instance, the FCC next week is expected to issue a decision on precisely what rates long distance competitors and others will pay to hook into the telephone network.

That could affect local phone rates directly, and, according to some analysts, could raise phone bills as much as $7 a month within a few years.

AT&T officials say, however, that local rates were heading up regardless of the shape of the divestiture. The company's general counsel, Howard Trienans, emphasized that in comments to reporters yesterday.

Other disclosures in the proposal:

An 8,800-employe Central Organization, supported by the regional phone companies, will aid in national defense planning and administrative and support functions. Trienans, hoping to forestall criticism of the organization's size, said it would not be involved in basic purchasing and marketing.

Residence Service Centers across the country will enable customers to call toll-free with questions about ordering, billing and repairs of in-place telephone equipment.

According to AT&T Treasurer Virginia Dwyer, the remaining AT&T company will retain 30 percent to 40 percent of the firm's one million employes. About 80 percent of the employes will remain where they are, she said.