WhatsApp, the tiny startup that connects most of the world, now has a brand new feature: push-to-talk voice messaging.

The service started out as a very simple idea, aiming to help users send and receive text messages between all types of mobile phones (not necessarily smartphones) on all different carriers in each country. While it started small, WhatsApp seems to have soared all the way to the top, with an impressive number of users.

WhatsApp told AllThingsD that it now has 300 million monthly active users. More than 20 million of those active users are each in Germany, Mexico, India and Spain. Jan Koum, the co-founder and CEO of WhatsApp, also detailed the new push-to-talk feature, which is also available on the app for BlackBerry and Nokia Windows Phone devices.

Koum is well-aware that being able to send a voice message is nothing new or special in today's slew of available messaging applications. At the same time, he highlights the difference WhatsApp can make.

WhatsApp's voice messaging stands out from the crowd due to its simplicity, points out Koum. More specifically, instead of having to tap several times through various settings or features, WhatsApp voice messaging keeps it simple: just press and hold while recording the message. Releasing the push will send the voice message to the designated recipient, while swiping to the left will delete it.

With the new update, WhatsApp has also simplified the process of listening and monitoring messages. In terms of listening, the app will automatically determine which speaker to use for playing the message, depending on whether the user is holding the handset up to the ear or at arm's length. When it comes to monitoring the messages, an icon shows when the receiving party has played the voice message.

WhatsApp sets no limit on how long a voice message can be, which means that users can leave a short message or share their whole life story, if they feel like it. The new voice messaging feature has already started rolling out to WhatsApp users and should hit all users across all platforms "within 24 hours," according to Koum.