WhatsApp started rolling out voice calling feature for
Android users earlier this year. It was available only
as invite-only option that opened occasionally, which
required a person who already have calling feature to call you to unlock it. Now, after the latest version (2.12.19) that can be side-loaded on your phone,
everyone using Android smartphones can enjoy
WhatsApp calling without invites. We tried it on
several smartphones, including smartphones running on Android Jelly Bean.

As it was said earlier, the call quality is decent on WiFi, but on 3G and 2G it was not the best. This might
improve over time. WhatsApp calling feature is currently available only on Android. It is expected to
roll out to other platforms soon. WhatsApp is yet to
launch WhatsApp calling officially. Since it is available for everyone, the announcement is expected soon.