I am currently traveling in Europe. No phone sucks (I’m on Verizon, which is CDMA, so I can’t use Europe’s cell towers). At least I can connect every once in a while, when I stumble onto a WiFi hotspot and at my hotel.
Without going crazy, I spent a little time researching how to SMS over WiFi. What I REALLY want is for my Android device to utilize WiFi for SMS so my texting threads (and contacts) still work, but that doesn’t seem to be an option (though there may be some promise when using Google Voice if you’re willing to integrate your “real” phone number with your Google Voice number).
The best (at least easiest and most apparent) solution I found was an app in the Market called textPlus. I set up an account that allows me to text over WiFi; they actually assign you a phone number and associate it with your account. Thus people can text you at this physical number, and you receive it through the app. I do have to import individual contacts into the app (hopefully this information isn’t being harvested by the app), and when I text people, they need to respond to this new number (all they need to do is respond in their texting app).
On the Google Voice front, below is a video showing how to use your Google Voice number to go back and forth with SMS and e-mail. This means you have to use your Google voice number for texting (not your phone’s actual number) and it doesn’t really get the messaging to streamline in your Android text threading. This may change if you integrate your actual phone number with Google Voice and then use your Google Voice number as your main device number, but I’m not willing to let big brother get that kind of a hold on my communication structure just yet.