When WhatsApp was released, it was a revolutionary best-selling app that provided users with the ability to text without having to pay for text costs or for data (if you used it on a WiFi network). Now, it may have taken one more step towards replacing the phone function of the device, and possibly even turning a user's iPod Touch into a phone.

WhatsApp's latest iOS update recently added the ability to make voice calls via the WhatsApp interface. Android users have had this function for a while, but it took a few weeks to fully deploy itself onto all Android-based WhatsApp users' phones. Early reports seem to imply the same thing with the iPhone version of the device.

What makes the iOS implementation of voice-calling function more interesting than the Android version is that this app will empower iPod Touch users with iPhone capabilities. While iPod Touch users have always had access to apps like Skype and other apps with calling capabilities, that feature was limited A) whether the other user had Skype or B) whether you were willing to pay for the service. However, the fact that WhatsApp has more than 800 million users increases the odds that the person you need to contact has the app as well. 

"With 800 million monthly active users on the WhatsApp service, this feature has the potential to upset a lot of carriers worldwide who have already seen their SMS revenues decimated by the rise of messaging apps. WhatsApp itself handles more messages from its users than there are global SMS sent each day. It's worth noting, though, that we don't know how many are on the iOS app," reports TechCrunch.

The update also added a number of other useful features, including "support for the iOS 8 share extension which allows you to send videos, photos and links to WhatsApp chats from other apps."