WhatsApp VoIP calling capabilities are not ready for their big debut just yet.

The Facebook-owned company has distributed the latest beta offering to testers for a glimpse of the service, giving us a look into how voice calling will be added into the WhatsApp service for iPhone, reports Redmond Pie.

iPhoneItalia has tested the iOS beta calling feature, and, according to Redmond Pie, the feature does not notify users upon initial launch. Only once a call is received by a fellow WhatsApp user is the service activated. The VoIP conversation can then begin.

Like typical cellular calls, users can respond to an incoming call with a preset, text-based message. Reminders can be set to call individuals back after a designated amount of time.

Users can receive calls when their device is locked or if using another app. 

It will work as an extension of the existing Phone app, except it'll be housed in WhatsApp. Best of all, calls will be completely free.

The general user interface is similar to the Phone app in iOS. It is nearly identical, which can be seen from the screenshots. iPhoneItalia also made a video that explains call quality is "decent."

The social messaging app reportedly has done well to emulate the native phone experience. When the VoIP calling service does launch, users should find it a pleasure to use.

Although no official announcement has been made when the WhatsApp VoIP calling feature for iOS will be released, if you are a WhatsApp user wanting to add VoIP to your iPhone, iGeeksBlog.com reports that there is an iOS jailbreak tweak currently available.

The WhatsAppCallEnabler Cydia jailbreak tweak developed by iMokhles allows you to establish the VOIP calling feature on your iOS devices. You can download it free from iMokhles repo.

Once downloaded, the tweak is disabled by default. You can enable or disable it from Settings app.

Keep in mind that you can call only other users who have enabled the WhatsApp VoIP calling feature. You can call Android users who have activated the VoIP calling service, too.