Verizon has agreed to pay a $7.4 million fine to the US Treasury for violating its wireline phone customers' privacy rights. The Federal Communications Commission said today that this “is the largest such payment in FCC history for settling an investigation related solely to the privacy of telephone customers’ personal information.”

The fine won't hurt Verizon's finances much, though: the company made $31.5 billion in revenue in Q2 2014.

An FCC investigation found that Verizon failed to notify 2 million new residential and business customers of their privacy rights, "including how to opt out from having their personal information used in marketing campaigns, before the company accessed their personal information to market services to them,” the FCC said. This deprived customers “of their right to deny Verizon permission to access or use their personal information for certain marketing purposes.”

The violations began in January 2006 and continued until after “certain Verizon personnel discovered a potential opt-out problem in [September] 2012,” according to the FCC order. Verizon “failed to notify the FCC of these problems until January 18, 2013, 126 days later,” the commission said. Verizon finally began sending additional opt-out notices to customers in March 2013.

“In addition to the $7.4 million payment, Verizon has agreed to notify customers of their opt-out rights on every bill for the next three years,” the FCC said.

The violations were in Verizon’s wireline telephone service, not its cellular business. US rules require traditional landline, VoIP, and wireless phone providers to obtain approval before using customer information for marketing, except to “market enhancements to services you already use.”

"For example, if you purchase basic local telephone service from a telephone company, it does not need your approval to use your customer information to try to sell you voice mail or caller ID service,” the FCC notes. However, the phone provider “must obtain your ‘opt-out’ or ‘opt-in’ approval before it can share your customer information within the company to sell you communications-related services you don’t already purchase; for example, to sell you long distance service if you only subscribe to local service.”