• by Wendy Davis  @wendyndavis, August 2, 2023

The advertising industry self-regulatory group Digital Advertising Alliance is launching a tool that aims to allow consumers to opt out of behavioral advertising techniques that rely on consumers' encrypted phone numbers.

The new mechanism builds on the organization's two-year-old “token-ID based tool,” which enables people to opt out of the use of their encrypted email addresses for behavioral advertising.

The phone number opt-out mechanism comes as ad-technology companies appear increasingly interested in drawing on identifiers such as email addresses or phone numbers for targeting.

Companies that deploy this strategy typically ask users for their email addresses or phone numbers, and use encryption techniques to convert those addresses or numbers into alphanumeric strings (or “tokens") that are used to track people and serve them with ads. 

The ad-technology companies participating in the initial Digital Advertising Alliance program include Adstra, Foursquare, IQM, Knorex, LiveRamp, Merkle, GroupM’s [m]Platform, and Tapad.

Consumers who go to the Digital Advertising Alliance's opt-out site can enter their phone number. Participating companies will then match the phone number to its encrypted identifier, and refrain from using that token for ad targeting.

The Digital Advertising Alliance plans to delete the phone number and encrypted identifier after 30 days.

The opt-out mechanism only allows consumers to reject receiving targeted ads tied to their encrypted phone numbers (or email addresses), and doesn't prevent companies from using those identifiers for other purposes, including measurement.

Privacy advocate Justin Brookman, Director of Technology Policy for Consumer Reports, expressed skepticism about the new control.

“This incremental tweak will go unnoticed and will do absolutely nothing to stem consumers' privacy concerns or the continuing tide of new regulatory proposals,” Brookman said in an email to MediaPost.

He adds that regulators are “demanding simpler and more powerful controls” than the self-regulatory group's AdChoices icon -- which aims to notify consumers about online tracking and offer links to sites where people can opt out of receiving targeted ads.

Twelve states now have privacy laws that require companies to allow consumers to opt out of targeted advertising, and at least four of those states -- California, Colorado, Connecticut and Montana -- require companies to honor opt-out universal signals that consumers send with mechanisms like the Global Privacy Control. That tool, developed by privacy advocates, transmits an opt-out command to every website consumers visit.