Cornelia Mitchell, 71, a widow and great-grandmother, can explain the symbols on her complex phone bill, understands the AT&T breakup and is adamantly opposed the telephone company's $31 million rate increase approved by the city's Public Service Commission in August.

Fearful that some of her elderly friends no longer would be able to afford a telephone if rates are increased, Mitchell sat through two consumer-sponsored daylong workshops on the telephone company. She then testified for the first time before the PSC against the company's request for a $54.5 million rate increase. The PSC approved the $31 million increase.

Mitchell was one of more than 170 persons who spoke at six public hearings during the year and is part of a growing number of ordinary consumers who have become active in battling rapid increases in telephone costs since the breakup of the Bell system.

C&P Telephone, which serves the District and nearby Maryland and Virginia, asked for the $54.5 million hike only seven months after the company had been granted a $41.9 million increase.

The public flocked to testify before the PSC, which usually hears from no more than 25 witnesses, including utility company representatives, on rate increases.

"I wasn't speaking for myself," said Mitchell, who lives on a fixed income in Southeast Washington. "I was doing it for the poor people who can't afford phones. . . .I have so many friends who don't have phones anymore because they can't afford it, so many people I've lost count."

Valerie Costelloe, a longtime Northwest activist who also testified, said, "I started talking to elderly people who said they were scared to death they weren't going to be able to afford a telephone. To many elderly people who only get out once a week, the telephone is the only thing that makes them feel like a human being."

Many city officials and community leaders credit the large turnout from the District's 37 Advisory Neighborhood Commissions and citizen groups from across the city with keeping the rate increase down to $31 million.

"There was a real concerted effort with a lot of public interest groups in fighting the rate hike," said City Council member Frank Smith Jr. (D-Ward 1). "I think they had a lot of impact on the decision."

Howard Davenport, general counsel of the three-member Public Service Commission, which rules on public utility rate increases, said the turnout at the C&P hearings "was much higher than the average compared to our other public hearings." Under pressure from citizen groups, the commission increased the number of public hearings held on the proposed rate hike.

Although C&P requested the increase in August 1984, most District residents did not learn of the proposed rate increase until January, when they received a notice with their monthly phone bills.

Christine Viezens, a North Cleveland Park ANC commissioner. "What that notice didn't tell me was that it the original request would increase my phone bill by 200 percent," said Christine Viezens, a North Cleveland Park ANC commissioner.

D.C. City Council member H.R. Crawford (D-Ward 7), said, "We had a large number of community leaders attend forums on this issue. I think that we're going to find an even more increasing number of people coming out to fight these utilities. . . ."

Webster Chamberlain, chief spokesman for C&P, said of senior citizens' opposition to the last two C&P rate hikes, "There's no question they senior citizens were well organized in both instances."

The PSC has yet to determine how the $31 million increase in basic telephone rates will be divided between business and residential customers.

To give the telephone company more money while that decision is made, the commission granted C&P an 8.62 percent across-the-board monthly surcharge on all classes of users except coin phones and Centrex business service. The surcharge will bring in and additional $13.7 million.

Mark Plotkin, head of the Glover Park ANC, who has been battling C&P for many years, spent much time during the year speaking at ANC meetings and going to door-to-door talking to residents in Northwest about the proposed rate hike.

"We think the three members of the PSC should be elected, and we're really pushing for that now" because the commissioners "have too much influence over the lives of D.C. residents . . . . ," Plotkin said recently. PSC members are appointed by the mayor and confirmed by the City Council.

The D.C. chapter of the Gray Panthers, a senior citizens advocacy group, has been hit hard by the most recent rate increase, said Ethel Weisser, a member for five years.

The Gray Panthers "have had a lot of people who used to make calls for the organization say they can no longer make those calls because they've switched to paying for each call," said Weisser. "The elderly are outraged and worried about how they're going to make it with these higher rates. . . ."