This document summarizes a research study that evaluated call availability prediction using a large dataset of 31,311 calls from 418 users. The study found call availability could be predicted with 83% accuracy using 15 basic features like time of last activity and screen status. Prediction was more accurate (87%) with personalized models. The top 5 strongest predictors were features related to time of last activity and screen status. The study demonstrated call availability prediction could be used to mute ringtones when unavailable or let callers check availability.