I want to communicate securely
There are two primary channels for communicating with others from your smartphone – using the mobile network (GSM, CDMA, etc) for voice and SMS messages, or using a data connection (e.g. to the Internet) over the cellular network. Different solutions for secure communications exist for each of the two channels, and each scenario below assumes both circumstances.
Generally speaking, privacy advocates and security researchers do not recommend using mobile phones or smartphones for (very) secure communication.
There is a third way, however, to communicate ‘off the grid’ for smartphone users. Firechat uses the phone’s wifi or bluetooth device to establish conversations with other users in the geographic vicinity. You do not need to connect to the cellular or data network. Messages between users in these temporal messaging rooms are, however, not encrypted.