How can I communicate with someone that only has a tablet? My wife and I recently ran into an unusal situation: She left her phone in my car, which I didn't know. I, of course, drove off with it. So we couldn't communicate by standard voice or text.

She did, however, still have our tablet with her. So I was wondering: what are the various ways that a person with a tablet can communicate with a person that has an Android phone (so never mind "borrow another phone" type answers)? I'd like as many different solutions as possible since, in this situaion, certain methods of commication (such as email) might be ignored as unexpected.
Here's a couple of answers to start with:


Email
Hangouts (or any other IM app), which usually require the other person to be logged in.
Glympse - Send a check-in glympse to their mobile number with a message. They'll get it as a text.
using some SMS gateway either via Web (browser) or a specific SMS app supporting this
using a messenger app like Tango, Skype, or LINE