Menlo Park, Calif.—Facebook Inc. has introduced a service that helps telecommunications companies analyze the relationship between Facebook ad impressions and sales. Called Telco Outcome Measurement, the tool goes beyond ad clicks, which Facebook said are a poor indicator of subsequent purchases. Instead, Facebook analyzes anonymous information about users' devices, operating systems and carriers, and links the information to users' exposure to Facebook telecom ads. The tool then determines a correlation with certain actions, such as switching to new phones, tablets or carriers, Facebook said in a statement. The tool is being made available to telecommunications advertisers on Facebook in the U.S. and eight other countries, with additional countries to be added through the end of the year, the company said.