Tengi

The app requires you to provide a phone number in order to create an account on the network, a profile picture and username. You can connect your Facebook account and import contacts from there. When your friends see the sent text, Tengi displays a confirmation message. You can send all sorts of files to your friends, including photos, videos, audio files and emoticons.
 
You can also set up groups and talk to friends on various topics. The app comes with some privacy options and tools for adjusting notifications. You can block users and change details under your account at any time. The app requires a SIM card in order to work on the phone, but it uses the WiFi network to send messages.