I've never liked a telephone of any kind as a means of online communication, except with a significant other when I happen to have one, because of its intrusive nature. This is why it was only several years ago that I started using a cellular phone, and a very simple one at that. It was only about one year that I finally started using a smartphone.
I have to admit that I've become quite addicted to my smartphone since then, but not to its telephone part but to the convenience of those various applications that have nothing to do with online communication. One of such categories is Torah study. Actually, I also have to say that my Torah study has been revolutionalized since I started using a smartphone about one year ago.
One area of my Torah study that has been affected most by this smartphone revolution is daily Torah study, to which I dedicate about half an hour right after I get up in the morning on weekdays and davening. The applications I use now are Daily Torah Study, Hayom, The Daily Sicha and Chayenu. I'm also planning (but haven't started) to use Steinsaltz Daily Study and Daf Hachaim.
A smartphone may not be an ideal electronic platform for reading lenghtly texts for an extended period of time, but nevertheless it's convenient and even assuring to have Torah libraries at my fingertips. I especially cherish Sefaria, RebbeDrive, and Igros Kodesh. When I daven outside (and sometimes even when I daven at home) on weekdays, I use Siddur Tehillat Hashem - Classic Edition. And last but not least, I check Chabad, Chabad Hebrew and Chabad Russian daily on weekdays to keep abreast of what's new in Chabad.