The study, conducted between July and The survey measured calls dropped or disconnected, calls not connected on the first try, calls with audio problems, failed/late voicemail notifications, voicemail with failed calls, text message transmission failures, late/failed received text messages, Web connection errors/failures to load, slow mobile Web, and email connection errors. Network performance issues are measured as problems per 100 network connections, with a lower score reflecting fewer problems and better network performance.