The explosive growth of the mobile phone industry has crowded and tangled the nation’s airwaves to such an extent that wireless company signals are increasingly interfering with emergency radio frequencies used by police and firefighters, public safety agencies said. Emergency departments across the country — including some in the District, Maryland and Virginia — report unsettling stories of officers who can’t call for backup, dispatchers who can’t relay suspect descriptions and firefighters who can’t request ambulances because of radio “dead spots” believed to be caused by wireless phone interference. “Just by the grace of God or good luck, we’ve been able to avoid a major problem,” said Gary Manougian, a police officer in Portland, Ore. “But I don’t think we can go on like this indefinitely.” Full Story