And e-mail will work when you don't even have a cell phone. I don't like the idea that I need to carry a phone around everywhere I go. If I happen to be carrying a laptop around with me, I want that laptop, as a more powerful device, to replace my phone, not require me to walk around with 2 devices which is cumbersome, theft-prone, and simply downright inconvenient to have your eyes glancing between 2 screens all the time. Everything else -- Facebook, Gmail, Skype, everything else -- can be accessed with that laptop. Information flows with me, independent of device. I show up in front of any screen that I own, authenticate myself with a password, and everything I need shows up on that screen, loaded from the cloud. I move between rooms, between offices, carrying nothing, and continue replying to my Facebook chats and e-mails that I started in the previous location. I don't need to carry anything with me. SMS, WhatsApp, and WeChat don't flow like that, which is why I hate them with a passion.

Plus, data plans are available everywhere now. For the most part, I use only data. Also, SMS doesn't work when you have to keep switching SIM cards and phone numbers. I can't login to half of my accounts that want to do SMS verification because I registered those accounts using a different SIM card in a different country; I have to wait till I return to those countries before I can login to those accounts and do something about them.

E-mail doesn't have this issue. I've had one e-mail address that has been associated with me for 15+ years that has worked 24/7 internationally. Phone numbers have to practically change every time you step across a country border. Phone numbers are a horrible way to identify me, at least.