SMS is a 2G phone function, so you can't send an SMS without cell service. (MMS is just an SMS with a link to a file sitting on a server somewhere.) There are apps that allow you to send and receive text messages to and from others - but they have to be using the same app.
What you're asking for (since it uses the same path) is the ability to make and receive phone calls without cell service. Skype (if you disregard the paid "call to a telephone" part, would work - if the other party had Skype. Same with SMS.
Google Voice is about your only option, AFAIK, for actual SMS at the moment. (Hangouts is text messaging, but not SMS.)
10-26-2014 02:46 PM