Facebook (FB -0.8%) roundup: 1) American users of Facebook's iPhone Messenger App users are now able to make free VoIP calls to each other. The move comes shortly after Facebook began testing the service in Canada. 2) Goldman argues Q4 results (due Jan. 30) could beat estimates on the back of healthy news feed ad sales and Gifts purchases. 3) Social media analytics firm SocialBakers recently estimated Facebook's U.S. and U.K. active users fell by 1.4M and 600K, respectively, in December (I, II). Seasonality likely played a role.