In an effort to cut Uncle Sam's housekeeping costs, many agencies are electronically blocking telephones so workers can't make personal long-distance calls. Other U.S. offices are installing sound-activated cutoff switches in federal bathrooms so that prolonged periods of silence result in the lights being turned off.

This high-tech war on waste has produced some savings. It has also spawned underground resistance from federal workers, some of whom survived building blackouts under Lyndon Johnson, chilly offices under Richard Nixon, pay parking and cold-only water faucets from Jimmy Carter and now a give-at-the-office drug testing program being pushed by Ronald Reagan.

These intrepid fed-up workers, whom government officials say represent only a tiny portion of the civil service, are fighting back with the tool they know best, the ultimate bureacuratic weapon: the memo.

A number of bogus memos and edicts, on official stationery and written in governmentese, dealing with phone policies and urine tests have reached this column. We haven't used them because they were either too long, too corny or unsuitable for a family newspaper. But just this week four readers (two federal workers, one contractor and the spouse of a concerned civil servant) have sent or hand-carried copies of an official-looking Pentagon directive that is making the rounds. Each asked if the memo is true and whether it is legal.

Pentagon officials say the memo is a fake. But the fact that some people think it is real gives you an idea of how things are going in the federal establishment. The memo in question reads:

"Washington Headquarters Services Building Circular. No. PBA-87037 Date: Sept. 18, 1987, Expiration: Permanent.

"SUBJECT: Restroom Policy.

"In the past employes have been permitted to make trips to the restrooms under informal guidelines. Effective Oct. 1 a Restroom Trip Policy (RTP) will be established to provide a consistent method of accounting for each employe's restroom time and ensuring equal treatment of all employes.

"Under this policy, a Restroom Trip Bank will be established. On the first day of each month employes will be given 20 Restroom Trip Credits. RTCs can be accumulated from month to month.

"Within the next two months the entrances to all restrooms in the Washington region will be equipped with Restroom Personal Identification Stations and computer-linked voice print recognition devices. As installation is completed each employe will be required to provide two copies of voice prints (one normal, one under stress). The voice print recognition stations will be operational, but not restrictive, during November. Employes should acquaint themselves with the stations during this time. If an employe's restroom trip bank balance reaches zero, the doors to the restrooms will remain locked for the employe's voice until the first workday of the following month.

"In addition, all restroom stalls are being equipped with timed paper roll retractors. If a stall is occupied for more than 3 minutes an alarm will sound, the roll of paper in the stall will retract . . . and the stall door will open."

Again, officials stress this memo is a fake. And that's for real.