It appears Telegram, the privacy-minded messaging app, is getting ready to add VOIP support to their Windows Phone app.
The latest update to the Telegram Preview app (similar to the WhatsApp Beta app) has added a section for calls (above), though users are not able to initiate or receive calls yet.
The update also fixes an issue with the Photos gallery, which is now able to display your various photo folders as usual.
The updated app is version 184.108.40.206 and is only available to those who downloaded the app when it was publicly available.
If you are one of the lucky ones you can find the updated app in the store here.