Basically, you can always contact me by e-mail. I´m not a huge fan of Whatsapp, but forced to use it anyway. Also can use mobile phones and tablets for some quasi-intelligent activity (that includes playing Solitaire games), and even do some Skype and other IM tools.
But I really live using mail and Slack (one for each community relevant to me), so go ahead and start contacting me by mail.