You can check out Loud-Hailer. (Full disclosure I work there.) We enable encrypted mesh networking with a mobile app, no need to buy a device. The messaging is embedded in two different city apps we have: Columbus2GO and Providence2GO. We've created engagement points throughout the city so you can receive hyperlocal content via the BLE mesh. You can also use the apps to message friends anywhere, just need to set up permissions. We're iOS only right now, but working on Android and SDKs.