At this point in time Samsung Z1 owners will only be able to call Android devices who has the updated feature, or other Samsung Z1 owners. This effectively brings the voice calling feature to two platforms – Android and Tizen, with iOS users left having to wait for their update which has been scheduled for a rollout in the coming weeks.
As pointed out by SamMobile, the reason why the Tizen version of WhatsApp managed to get this feature ahead of a more “prominent” platform like iOS is because the Tizen version of WhatsApp is an emulated version of the Android app. This means that it is possible for Tizen users to receive the same updates and features as its Android counterpart without too much fuss or hassle.
Like we said iOS users will still have to wait a couple of weeks for their feature, and there’s still no word on when voice calling will be rolled out to users of BlackBerry or Windows Phone platforms.