I've decided to use bluetooth as my protocol as you can transfer files such as a picture to another contact. It is reasonably quick to send the file and it is simple to use but a downside is that if the file is very large it will take longer and in the meantime your battery could run low or even run out during the process of sending the file. An alternative to bluetooth is SMS, the positives of using SMS are, it is also simple to use and you can message from anywhere it is also sometimes to cheap to use depending on which network you are on, the negatives are that the message could fail or you could send it to the wrong person.
