Chesapeake & Potomac Telephone Cos. and a New York-based partner began offering a new service last week that allows Washington stock-market gazers to punch in symbols for companies they track and get stock quotes over a touch-tone phone.

The service, called Stock Fone, provides three minutes' worth of stock quotes for 50 cents. Fast-fingered customers should be able to get up to 30 stock quotes, said Andrew Batkin, president of International Information Network Inc., C&P's partner in the venture.

"Washington, D.C., is the first city, and we plan seven cities to have the service by the end of August -- Atlanta, Baltimore, Miami, Philadelphia, Los Angeles, San Francisco," he said. Baltimore and Philadelphia should have the service in early August, he said.

Batkin projects the service will generate 60,000 to 90,000 calls a month in a city the size of Washington within the first three months of operation. C&P and IIN will split the income, he said.

"You call 976-STOCK. You need no special equipment," said Web Chamberlin, spokesman for C&P. "You enter the ticker symbol for your stock -- each time you press one of the push buttons on the phone you give our computer a signal."

To call up a stock quote, a user must punch in standard stock symbols using the letters on the telephone buttons and then hit the numeral sign to the right of the operator key twice.

For example, a caller wanting a CBS Inc. stock quote must punch the "2" key three times to identify the letter "C," which is in the third position on that key. The user then must hit the "2" key twice because the letter "B" is in the second position, and the "7" key three times to indicate the letter "S." The user also must hit the numeral sign once between punching in the letters "C" and "B" because they both are on the same number "2" key. After punching in the stock code, the user must hit the numeral sign twice to get a quote.

But the process can be shortened considerably; users can assign themselves a code and program the symbols for which they want quotes, Batkin said. Thereafter, the user calls up the computer number and punches in his or her code and the numeral sign twice to get up to 30 quotes automatically.

The service is 24-hour, and during trading hours stock quotes are delayed 15 minutes. A computer voice reads the stock quote and any change from the previous day's closing.