The app WhatsApp which is a social media
tool for communication has now been updated
with the presentation of beta version for the
iOS operating system, which is version
2.18.110.17 beta. It has an improved interface,
including group phone calls ability. 
A statement released by WABetaInfo , thanks to
this increase, WhatsApp users on iOS devices
will see a new group call button in chat in the
group.
I noticed it when i was on call with a friend
and made my research before this post is
been published.
The messaging service today has a community
of more than 1.5 billion monthly users and
added voice calls a little more than three
years ago, with video calls a year after that. In
addition to the calls being end-to-end
encrypted, WhatsApp says they’ll work reliably
around the world even under different network
conditions, and the new feature is rolling out
to both iPhone and Android versions of its
app.
The moment you are on call, a group call icon
will be displayed on the right corner of your
phone and When this group call button is
tapped, the user will see a list sheet for all
group members that can be selected to start
group phone calls. For this purpose, only
friends that are registered in the address book
can be seen by the user.
On this platform of whatsapp group calls,
users can only involve three friends to chat
together through phone calls. If the user
selects more than three, a reminder notice will
be displayed.
Unlike the previous version, group phone calls
must start with a normal call before then
adding other friends to be involved, in this new
version group calls can be run more easily.
Also, the latest update of the beta version
released now has some cool updated features
like GIF files that used to stop unexpectedly
has been improved upon.
Others include fix problems like when users
download and upload stickers, fix bugs when
users are added or dismissed as group Admin,
and fix problems when users search for chat,
contacts, and messages.
Source: digiconcept.