TextPlus and Talkatone, for iOS, Android, and Windows Phone, all set you up with a new number/address and allow you to make phone calls and send text messages over a data network like Wi-Fi. You could try a VoIP option to replace your carrier-monitored phone calls, but those are not always more secure. BlackBerry Messenger, which has its own encryption, is similar–although its encryption doesn’t work when the police seize your phone. It’ll take advantage of Wi-Fi if you’re on a Wi-Fi network, which is a good thing to do whenever it’s available–it’s much harder for your wireless carrier to monitor (or, less scarily but more annoyingly, to wildly overcharge for) Wi-Fi use. Apple’s iMessage, which communicates between Apple devices, uses a data connection that is not routed through your carrier’s servers the way SMS texting is.
