Problem: Fraud over the telephone costs banks and retailers more than $1.8 billion a year. Criminals who call customer service lines pretend to be legitimate customers and often dupe the operators into approving a transfer or divulging sensitive account information. 

Solution: Vijay Balasubramaniyan can detect where a call is coming from by analyzing its audio quality and the noise on the line. If a call purportedly from one place has the audio signature of a call from the other side of the world, his technology can sound an alert. The company he founded, Pindrop Security, counts several banks and an online brokerage firm as customers.

The audio quality of a phone call is affected in subtle ways by many factors, including the networks and cables it travels through. Pindrop makes hundreds of phone calls per hour to build a database of what, for example, a cell phone on a particular network in India sounds like. The service can then compare those files with the audio patterns in calls to customer service centers to determine whether a call is coming from where it says it is. 

—Conor Myhrvold