Voice calls are the latest addition to the hugely popular WhatsApp messaging service.
The new feature allows users to make free phone calls to WhatsApp contacts, wherever they are in the world.
WhatsApp calls, which require a mobile or Wi-Fi have been available on Android since the start of the year but were only recently added to the iPhone app.
But a shocking test by AndroidPit has revealed that WhatsApp uses 1.3Mb of data per minute when making a phone call.
This is not a problem if you are connected to an unlimited WiFi hotspot – but WhatsApp could quickly romp though a restricted 3G or 4G plan.
Chatting away at a rate of 1.3Mb of data per minute will burn through a 500MB monthly data plan in just SIX hours – which is equal to 11 minute of call-time per day.
By contrast Voice over IP app Viber claims to use 240Kb per minute during phone calls.
Voice over IP, which is available from a number of providers including FaceBook Messenger, Google Hangouts and Apple FaceTime, can provide a much-clearer connection than traditional cell networks.
However the rise in Voice over IP – dubbed VOIP – means having enough data is becoming a growing issue for many smartphone fans.
Internet calling, on demand video content and music streaming mean users are now using more data than ever before.
Unlimited calls and texts are common on most modern contracts but data is often limited and – if you want plenty of it – you will have to pay a hefty price.