The United States has acknowledged that it suspects that cellphone spying devices exist in Washington. It says the devices could be permitting foreign spies and criminals to follow an individual’s movements, secretly listen to calls, and read text messages. The devices are called cellphone-site simulators. American intelligence and law enforcement agencies use the equipment themselves. However, they have been quiet about the issue of such equipment being used against the U.S. Ron Wyden is a Democratic Party lawmaker from Oregon. Last year he requested information about simulators in a letter to the Department of Homeland Security. Last week, the DHS answered Senator Wyden by letter. It said the DHS had identified suspected illegal cellphone-site simulators in the nation's capital. The letter said the agency did not know the kind of devices in use or who might have been operating them. It did not give more details.