The telephone rang at the sales office of a Baltimore television station. It was a time-buyer at the advertising agency for Acting Gov. Blair Lee III, calling to find out precisely what commercial time the station had sold to opponent Theodore G. Venetoulis for the final days of the Democratic primary campaign in Maryland.

"Okay," said the Lee representative, after getting a report on the Venetoulis television schedule. "We'll buy the same times."

As soon as the Lee time-buyer hung up, the sales manager took another call. Now it was the advertising agency for Venetoulis on the line. "Will you tell us," came the question, "what times the Lee people are buying?" The Lee advertising schedule was recited over the phone and again the conversation ended with the words, "We'll buy the same."

"It's crazy, what the politicians are doing this year," the sales manager said minutes later."They always want to know what the opposition is doing so they can do the same thing. I've never seen it like this before."

Crazy or not, what the sales manager had just experienced was something that has been occuring with increasing regularity this year. Lee, Venetoulis and many other Maryland politicians are embracing television advertising with more money and vigor than ever before.

And with that embrace has come a closer scrutiny of what their opponents are trying to project in their ads.

This week several radio stations began playing 30-second commercials for Lee that were harshly critical of his chief opponent - Venetoulis. One such negative ad charged that Venetoulis attempted to raise the property tax rate by $1 during his first year as Baltimore County executive, a charge that Venetoulis says is 91 cents off the mark.

The Venetoulis media experts knew that they could not force the ad off the air. (The prohibition in a southern state was recently allowed to push an ad about getting rid of "niggers"). By complaining loudly enough to the radio stations and to Lee's ad agency, however, they managed to get the agency to withdraw the spot from several stations.

A Lee spokesman defended the anti-Venetoulis advertisements by arguing that Venetoulis, more than any other candidate, has attempted to portray himself as a larger-than-life figure during the campaign and that the ads merely "showed him for what he is and what he's done." Venetoulis, in response, said the ads were "an act of desperation by a foundering campaign."

Only a few days earlier, supporters of gubernatorial candidate Harry Hughes were upset by another Lee radio spot that concentrated on praise for the acting governor from the Baltimore Sunpapers. Hughes argued that the ads implied that the Sunpapers had endorsed Lee, when in fact they endorsed Hughes in editorials that were anything but kind to Lee.

Hughes, who went on television several months ago for a three-week advertising campaign, has only this week found enough money to return to the air with a last-minute blits. His own ads, while not as negative as Lee's anti-Venetoulis radio spots, do include one sentence that refers to "the acting governor and another fellow who is not a bad actor himself (read Venetoulis)"

The flaps over the content of political advertisements signal just how essential electronic campaigning has become in Maryland. "Time buyers" and "adjacencies" (spots that come just before or after a show) and "primes" are now as much a part of the state's political vocabulary as "bull roasts" and "ward heelers." The Federal Communications Commission regulations are now as important as those of the state elections board. The "Political Broadcast Catechism" is as well read as the "Almanc of American Politics."

All of that is true, at least, for the candidates who have enough money to play the television and radio advertising game. For, despite all the federal regulations intended to make access to the airwaves as equal as possible, political advertising is still bought, and it takes a lot of money to buy it.

Consider, for example, what it cost to get two 30-second political spots on ABC's "Roots," the highest-rated television show on the air during the last week of the primary campaign. The network's local affiliate in Washington, WJLA, charged candidates $3,500 per 30-second spot. The Baltimore affiliate, with smaller market, charged $2,000 for 30 seconds of air time on the week-long serial.

Lee, who has raised nearly $700,000 for his campaign, and Venetouils, whose treasury is approaching $500,000, each spent $11,000 for two minutes worth of advertising time on "Roots," and still had enough money left to saturate the other stations with political commercials. The other two Democratic candidates for governor - Hughes and Walter S. Orlinsky - would have drained their modest treasuries just to get on "Roots" for one minute.

Baltimore County adman Louis Rosenbush, who is overseeing Lee's heavy media campaign, said be was surprised that he could get his candidate on "Roots" at all. "It isn't like it used to be," said Rosenbush, who has been in the political advertising business since the advent of television. "There was a time when we could buy whatever we wanted - the choicest, prime-time stuff. Now most of what the stations give us is garbage."

Rosenbush was examining a schedule of shows that a Baltimore station listed as open for the purchase of political commercials. "Hogan's Heroes, Morning Rotation. Tabitha garbage."

Most station managers deny the adman's complaint that politicans are offered the dregs of television time.

"We try to be fair about it," said Rennie Corley, the assistant general manager at WMAR-TV in Baltimore. "The politicians know that when they buy prime time from us it means they'll get their spots on anywhere from 8 to 11 p.m. We try to give them one good one, one mediocre one and one bad one within that period."

Still, Corley's station has imposed a limit on the number of political spots it will take from any candidate, with the prime-time maximum set at three a week. Virtually every other television and radio station in Maryland and Washington, D.C., has some sort of limit - ranging from radio station WWDC in Washington, which accepts no political advertising, to WBFF-TV in Baltimore, which will sell time for everything except University of Maryland football broadcasts.

In selling time to politicians, the television and radio stations must adhere to a set of federal regulations so lengthy and complex that nearly every station interprets them differently. The three regulations that the politicians and their admen are most interested in require the stations to sell time to candidates at the "lowest unit rate", and give a candidate the same time slots as his opponent if that is requested.

The equal access regulation explains why Lee and Venetoulis admen have spent so much time checking with stations to see what the opponent is doing. Frank DeFilippo, a Rosenbush assistant who once served as press secretary to suspended governor Marvin Mandel, has noted with pride the time he discovered that Venetoulis had purchased four radio ads for a Labor Day broadcast of an Orioles-Red Sox baseball game.

"The guy said he'd sold all the time to Venetoulis," recalled DeFilippo. "So I said: "Well, give me two of his." They had to do it, that's the law."

The stations have a little more flexibility with the law requiring them to give candidates the "lowest unit price" starting 45 days before the primary election and 60 days before the general election. That price is supposed to reflect the lowest rate the station has ever charged for a certain time period. Some station take the trouble to calculate that price: others simply charge the candidates a fixed cur-rate.

The stations can ignore the lowest rate requirement altogether if the political spot does not include the voice of the candidate, which explains why, at the end of virtually every radio advertisement, one hears a brief tagline with the candidate saying: "Hi, I'm John Doe and I'm asking for your vote . . ."