Phone fraud prevention and call center security company Pindrop Security recently announced the close of an $11 million Series A investment round led by Andreessen Horowitz and Citi Ventures, and including Redpoint Ventures, Felicis Ventures, and Webb Investment Network.

"Enterprises, and particularly financial institutions, are facing increasing volumes of attacks from sophisticated social engineering operations," Pindrop cofounder and CEO Vijay Balasubramaniyan said in a statement. "Pindrop's solutions are the first tool for financial institutions and enterprises to detect and stop these attacks accurately and consistently on the first call. This investment will allow us to meet the tremendous market demand we're experiencing."

According to Pindrop, the funding will be used to deploy additional resources in engineering, operations, sales and marketing in the U.S., Canada and Europe.

Scott Weiss, general partner at Andreessen Horowitz, will join Pindrop's board of directors. "Phone systems are the weakest link in fraud and authentication for corporations and attackers are exploiting that," Weiss said in a statement. "Pindrop Security has a world-class team tackling this problem. Their unique acoustic fingerprinting technology allows customers to predict unknown fraud, identify repeat criminal rings and transparently authenticate legitimate customers."