At the risk of talking about the actual topic at hand instead of diving off into minutia about putting SSH on your phone, I'm not sure what this gets you, from a paranoia point of view. Assuming the idea is that you want 100% coverage of your server, this might marginally increase your odds, but not really all that much. Times when you aren't available to administer your server are likely to correlate highly with the times when your buddy isn't available. And what if you'd never gotten the SMS in the first place because you were entirely out of service?

One person simply can't cover a server 100%, adding a "buddy" doesn't help much. Either you need a full-on netops operation, or you need to be able to deal with not having 100%.