The telephones were already ringing and the titles were on the doors by midafternoon yesterday as the Reagan administration transition team set up shop here, beginning work on appointments and executive orders the Republicans hope will produce a clear sense of change during Ronald Reagan's first three months in the White House.

Equipped with a $2 million federal bank account, seven floors of federal office space (1726 M St. NW) and a big bank of telephones (634-1981), the transition team eventually is to grow to an operation of 250 people run by Edwin Meese, Reagan's chief of staff.

In an interview in Los Angeles, Meese predicted that the first 90 days of the Reagan administration will demonstrate clearly that the new president intends to bring about significant change in the federal establishment. He identified four basic areas on which the government-in-waiting will focus in the weeks before Reagan's inauguration Jan. 20.

Meese said the transition office will study the president's executive authority, looking for early actions Reagan might take to set a tone for his administration. Reagan aides have suggested that a freeze on federal hiring and rescission of some controversial regulation might serve to dramatize Reagan's commitment to reduce the size and scope of the federal government.

Meese said a personnel office, to be headed by former Nixon administration personnel official E. Pendleton James, who now runs a Los Angeles executive recruiting firm, will search for people to fill the 2,700 top-level federal jobs at the president's control.

Meese said he thinks the "mandate" of Reagan's big victory will help the new administration lure into government service business executives who might otherwise spurn federal salaries and the insecurity that comes with an appointive post.

An "executive liaison" operation will be established, Meese said, to send teams into each major federal agency and coordinate the transfer of power. Another liaison office will work with Congress to develop an initial legislative program.

A budget planning group will work with Congress on final details of the current (fiscal year 1981) budget and develop a Reagan administration budget for fiscal 1982. Carter will submit his 1982 budget before he leaves office, but the new president will then propose his amended version.

Reagan is to announce soon, possibly today, the name of his chief budget planner. Likely candidates would include Caspar Weinberger, a budget director and secretary of health, education, and welfare in the Nixon administration, and Vern E. Orr, who was controller of Reagan's campaign committee.

The review of the president's authority to issue executive orders is getting high priority in the transistion operation for two reasons:

Reagan reportedly wants to issue such orders early in his presidency so that he can be seen to be making quick change; an executive order gets things done without waiting for action from Congress.

The Republicans want to review all pending presidential orders to determine whether Carter has launched any new policy actions Reagan might want to block.

The transition group will rely on dozens of reports prepared by advisory groups established by Reagan during the campaign, and by a variety of think tanks ranging from the rightist Heritage Foundation and Hoover Institution to the Institute of Politics at Harvard's John F. Kennedy School of Government.

The president-elect also has said he will confer with various blue-ribbon advisory groups. Some, such as his educational task force, seem to be made up mainly of conservative thinkers. Others include representation from both major parties. Reagan's foreign policy advisory committee, for example, ranges from Republicans like Henry A. Kissinger and Sen. John G. Tower (R-Tex.) to Democrats such as Sen. Richard Stone of Florida and Washington lawyer Edward Bennett Williams.

A major part of any transition is the talent scout operation, for a new president can fill hundreds of jobs paying more than $50,000 annually and hundreds more at only slightly less. The basic text on this subject is a quadrennial government publication officially titled "Policy and Supporting Positions," but more commonly known as "The Plum Book." The 1981 edition, listing about 2,700 "plum" jobs that Reagan and his appointees will fill, will be published next week, according to the federal Office of Personnel Management.

Although Pendleton James, who will serve as chief talent scout, has not arrived at transition headquarters, campaign aides said telephone calls and resumes had already begun to arrive. In addition to those who submit their own names, the president-elect's team expects to receive countless recommendations from Republicans on Capitol Hill for various federal positions. Also, the Heritage Foundation has compiled a "talent bank" of prominent conservatives for the transition office to consider.

The Reagan campaign began quiet planning for a Republican administration in September. A "Presidential Transition Trust," supported by a small group of individual contributors, was established to fund a low-key transition operation that has been operating in a walk-up office in Alexandria under the direction of Washington lawyer Peter McPherson.