Michael Darr Barnes, Montgomery County member of the Maryland Public Service Commission, said last week that he believes the Chesapeake and Potomac Telephone Co. should be allowed to charge commercial firms for making information (411) calls, but not residential customers.

Barnes said he is convinced that residential phone users have been subsidizing commercial firms on the cost to the company of directory assistance because many firms make volume calls through information whereas few individuals use the service regularly.

He also said he thinks a bill to this effect will be introduced in the present session of the Maryland General Assembly.

The House of Delegates last week sustained Gov. Marvin Mandel's veto of a bill, that would have prevented the telephone company from charging anyone for information calls.

That cleared the way for the company to ask the PSC to grant authority to begin charging for the 411 service.

Barnes said that although he doesn't want to "prejudge" a specific case that may come before the PSC, he has studied the issue, analyzed the information submitted to the legislature and concluded that it is fair to charge commercial firms but not residences.

The other two Public Service commissioners, chairman Thomas J. Hatem of Harford County and William S. Baldwin of Baltimore County, said they thought the proposal discussed by Barnes had "some merit," but they will wait to be presented with a case before indicating their views.

All three commissioners mentioned testimony before the legislature by C&P showing that one business used 411 to make more than 20,000 calls in one month.

"Some businesses, like a credit checking firm, have to use directory assistance," Barnes said, "but residential customers shouldn't have to pay for it."

Any C&P effort to push the 411 charge could be delayed by its Nov. 5 request to the PSC for an $82.3 million rate increase - an overall rise of 12.7 per cent that would cost a typical customer $1.90 per month. That includes a proposal to double the phone booth cost of calls from 10 cents to 20 cents, the first increase in 24 years, C&P said.

C&P claims that taxes would take about half of the proposed increase. Hearings begin Jan. 26 and the PSC must decide the case by May 5. A large number of organizations oppose the increase.