BALTIMORE -- The new companies offering pay telephone services in Maryland say their main competitor, Chesapeake and Potomac Telephone Co., knows nearly everything about them but they know little about it.

The Maryland Public Service Commission gave the private companies permission earlier this year to install their own pay phones. Hundreds have appeared since then, some replacing C&P phones. The state Public Service Commission has approved more than 2,800 applications to install pay phones at various locations. While more than 350 companies have submitted applications, about 10 of those companies submitted more than 70 percent of the applications.

The commission case allowing the new era in pay phone competition is still open and the issue will be reviewed by a commission hearing examiner early next year.

The new companies must rely on C&P to service their equipment.

C&P also knows exactly how many phones each of its competitors has and how many calls are made from each set, since C&P gets 10 cents for every call.

But such information about C&P is not available to its competitors. C&P spokesman Al Burman said such information is "market-sensitive."

"It's very frustrating," said George L. Wood, president of U.S. Pay Phone Co. Inc. "We know very, very little about them."

C&P denies it is doing anything wrong. "We are providing service to all vendors on a uniform and nondiscriminatory manner and that will continue," Burman said.

Asked if C&P is using the information about the activity at competitors' phones in locating new phones, Burman replied, "not to my knowledge."

While the private pay phone companies complain about C&P's actions, they often use telephone boxes that look remarkably like the blue and silver C&P phones.

"Customers are used to that type of phone," Wood said. As to accusations that he is copying C&P, "I don't have any problem with that," he said.

U.S. Pay Phone is the largest non-C&P pay phone operation in Baltimore with 450 phones in the area, 350 of them within the city limits, Wood said.

The company, which is based in Washington, has 1,100 pay phones in Maryland, the District and the northern Virginia area.