Of course we agree on the fact, that cellphones aren't that good in the great outdoors cause they just don't work if you are too far from civilization. That's why we use devices like Walkie-Talkies etc.
So, since everyone of us has a smartphone already, is there any hard- or software to transform these into outdoor-prove devices? So that I can stay in contact with my group even if there isn't any connection to the mobile network (and wifi of course)?!
Aravona added a good point. It's eventually even cheaper to buy a common walkie-talkie than a phone-addon (especially if it's something like iWlkieTalkie ;P). However, just share your thoughts nevertheless if it would be more expensive.
Edit:
This question is about connecting smartphones together not about interconnecting walkie-talkies and smartphones.
The situation is like this: me and my buddy do any kind of outdoor activity where we neither have wifi nor mobile network. Nevertheless we want to stay connected. Since we both already have a smartphone I wondered if we can connect these two smartphones, so that we can use them to speak/text to each other.