Android users have yet another option for data-only calls and text messages today, as BitTorrent Inc. posted an alpha version of its Bleep communication client to the Play Store. Bleep is designed to be an alternative to conventional calling and texting systems like Skype or WhatsApp, and requires no central server or service. Bleep has been invite-only since July, but now it's ready to go public. Clients are also available for Windows and OS X computers.
The core idea here is privacy: because Bleep makes a person-to-person connection with no middleman, there's no way for anyone to hack in via remote and get to all that sweet, sweet, personally-identifiable communication. That's the idea, anyway - if certain three-letter organizations want to peek in on you, there are other ways for them to go about it, but Bleep is aimed at closing at least some of that vulnerability.
Chat messages and voice calls are free in Bleep, but currently there's no way to ring "real" phone numbers (except the ones that are associated with a Bleep profile, à la WhatsApp, and that's not really a call). You can import your address book and invite your contacts to download the app via email or a conventional SMS text, or just send them your public key. You can also swap information via a QR code in person. An incognito mode is supported; while it's active no one will be able to find you with a search for your number, email address, or nickname.
Bleep is pretty barebones at the moment, but that's to be expected for an alpha. Give it a go if you'd like to try out a semi-secure and novel approach to data calls and texts.