Twitter apologized for repurposing phone numbers provided by users for security features for use in targeted advertising. Phone numbers provided for security were fed into its targeted advertising tool called Tailored Audiences. Twitter doesnt reveal to advertisers the contact information it has collected. It’s generally considered a violation of privacy norms in the U.S. but could be allowed under Europes General Data Protection Regulation under the purpose limitation principle, a lawyer and privacy engineer says. Twitter’s disclosure comes just three months after Facebook received a $5 billion fine from the Federal Trade Commission for a range of transgressions.”]
Source: https://www.govinfosecurity.com/twitter-apologizes-for-repurposing-phone-numbers-a-13224