My reaction to XKCD is normally come either as “it flew well over my head” or “it was so spot on”. This is possibly the first time I have the third reaction; it’s just great, but I disagree on a detail. 
A recent piece elaborates over means of communication, and also points out the fragmented islands that the OTT IM solutions form. But ALL should be reachable via SMS. SMS is the universal service that comes with ALL mobile phones (you can’t uninstall the SMS app, you can’t disable it – it is there, period), it’s supported by ALL mobile operators, in ALL countries.
So whereas Randall Munroe is one of my heroes (and I’m so disturbed that we never met on the 0redev, where we both where supposed to have keynote speeches – I just missed mine as I left for Myanmar) I have taken the liberty of doing an utter layman’s change to prove my point:
All rights to the original belongs to Randall, and I apologies in advance for the artistic mutilation of his work.
 Not entirely true. This one is an example where I got it and disagree. Licorice is an acquired taste, and as they say “once you go black, you can’t go back” which is at least true for candy! 🙂