“The bad guys are beating the good guys with technology,” Wheeler said. In the past, he has said robocalls continue “due in large part to industry inaction.”

Stephenson emphasized “the breadth and complexity” of the problem.

“This is going to require more than individual company initiatives and one-off blocking apps,” Stephenson said. “Robocallers are a formidable adversary, notoriously hard to stop.”

The FCC does not require robocall blocking and filtering but has strongly encouraged phone service providers to offer those services at no charge.

The strike force brings together carriers, device makers, operating system developers, network designers and the government.

“We have to come out of this with a comprehensive play book for all of us to go execute,” Stephenson said. “We have calls that are perfectly legal, but unwanted, like telemarketers and public opinion surveyors. At the other end of the spectrum, we have millions of calls that are blatantly illegal.”

Stephenson said technical experts representing the companies have had “preliminary conversations about short- and longer-term initiatives.”

Joan Marsh, AT&T vice president of federal regulatory issues, called the problem complicated. “We have been wrangling with this problem long enough to know there is no silver bullet,” she said. “Nothing by itself is going to do it.”

Other companies taking part include Blackberry Ltd (BB.TO), British Telecommunications Plc [BTCOM.UL], Charter Communications Inc (CHTR.O), Frontier Communications (FTR.O), LG Electronics Inc (066570.KS), Microsoft Corp (MSFT.O), Nokia Corp (NOKIA.HE), Qualcomm Inc (QCOM.O), Samsung Electronics Co Ltd (005930.KS), Sirius XM Holdings Inc (SIRI.O), T-Mobile US Inc (TMUS.O) and U.S. Cellular Corp (USM.N).

Consumers Union, a public advocacy group, said the task force is a sign “phone companies are taking more serious steps to protect their customers from unwanted calls.”