Bangalore became know as India's Silicon Valley in the late nineties,and these day it is one of the world's principal call centers.Multinational corporations freuently hire companies in India to handle services to their customers over the phone:everything from technical support on computer help lines, to credit card transactons, to telemarketing calls selling insurance and vacations,to filling catalogorders.So now,customers in Europe and America commonly talk to phone workers in Bangalore.