Twitter revealed that it "inadvertently" used phone numbers and email addresses users provided for security purposes to deliver targeted advertisements. According to CBS News, the company said that the information that users had provided for two-factor security authentication was used by advertisers to match members to their own marketing lists. Twitter cannot say with certainty how many people were impacted. According to the BBC, Twitter, which is headquartered for Europe in Dublin, would not confirm whether or not it had notified the Irish Data Protection Commissioner.