Despite mounting pressure to lift the ban on cell phones in the city’s public schools – the only such prohibition among the nation’s big cities – Mayor Bloomberg is refusing to budge and appears to be losing his patience with the topic.

“What do you mean a compromise? You can’t use cell phones in school and you can’t use iPods – why can’t you get the message?” Mr. Bloomberg said yesterday when reporters asked about the ban at an unrelated event in Brooklyn.

Among the 10 largest school districts in the country, New York City imposes the only total ban on cell phones in school buildings. The second largest district, Los Angeles, prohibits use during the school day while allowing students to carry phones in their backpacks. Policies in other districts vary from no restrictions at all to allowing principals to make their own decisions.

The county where Las Vegas is located lifted its ban almost three years ago and now allows students to carry phones, but restricts their use to during the lunch period.

“Parents wanted to be in contact with their children,” a spokeswoman for the Clark County schools, Pat Nelson, said.

Until this school year, Philadelphia, the seventh largest school district in the country, forbade students from carrying phones in school. In September, the district started allowing principals to decide.

The ban on cell phones in New York City dates back to a 1987 policy that forbade students from carrying beepers and other electronic devices to school. In recent years, many schools opted not to enforce the ban as long as students turned their phones off during class and kept them out of sight.

The issue flared up last month when the Bloomberg administration started random metal detector searches in city schools. Intended to catch students carrying weapons into class, safety officers instead began confiscating cell phones, iPods, and CD players.

Some parents and elected officials across the city are protesting loudly against the policy. Yesterday, the president of the United Federation of Teachers, Randi Weingarten, led a demonstration outside Middle School 51 in Park Slope, Brooklyn.

“Cell phones are a lifeline for many parents and children,” Ms. Weingarten said. “After 9/11 and the Roosevelt Island tram incident, it is obvious we need a way for parents to make sure their children are safe.”

The UFT’s executive board recently passed a resolution urging the schools chancellor, Joel Klein, to allow students to bring the phones to school but to prohibit their use in school buildings.

Mr. Bloomberg appears unfazed by the opposition and steadfast in his unwillingness to compromise.

“He’s going to be the mayor for the next three-and-a-half years and he has no intention of running for another office, so if he wants something he’s not going to worry about the consequences at the polling booth,”a political consultant and lobbyist, Norman Adler, said.

A spokesman for the chancellor, David Cantor, said other cities, such as Baltimore and Detroit, have similar rules on the books. “We have found that enforcing the ban is by far the only way to maintain an orderly learning environment,” he said.