A call made by an unidentified person stating that a bomb was planted at Noble College of Engineering and Technology for Girls at Nadergul and it would explode within 3 minutes had turned out to be a hoax on Monday. The miscreant made the call to college secretary Anasuya from a coin box public telephone around 9.45 a.m. On receiving information, the Cyberabad police pressed into service bomb disposal and dog squads and checked the premises. The squads later declared that explosives were not found in the college, said Meerpet Inspector P. Sridhar Reddy.