Twitter stores full iPhone contact list for 18 months, after scan

Twitter has acknowledged that after mobile users tap the "Find friends" feature on its smartphone app, the company downloads users' entire address book, including names, email addresses and phone numbers, and keeps the data on its servers for 18 months.

The company also said it plans to update its apps to clarify that user contacts are being transmitted and stored. The company's current privacy policy does not explicitly disclose that Twitter downloads and stores user address books. It does say that Twitter users "may customize your account with information such as a cellphone number for the delivery of SMS messages or your address book so that we can help you find Twitter users you know." As with many online social services, Twitter allows users to look for friends that are also registered users. In the case of Twitter's iPhone app, users see a screen noting that the service will "Scan your Contacts for people you already know on Twitter." The short description of the feature does not mention that it also downloads every entry in the address book and stores it. Twitter's current privacy policy notes that some categories of "Log Data" are stored for up to 18 months.