Mobile messaging service WhatsApp is rolling out push-to-talk voice messaging today for all of its apps on the iPhone, BlackBerry, Android OS, Windows Phone and Nokia, the company’s co-founder and CEO Jan Koum told AllThingsD.

The update is expected to be available to all users within 24 hours.

In the updated version of WhatsApp, the walkie-talkie-like feature will let users push to record a message, and upon letting go, the message gets sent. If you decide not to send the message, all you have to do is swipe to the left and the recording gets deleted.

There is no cap on the length of recording, and a blue microphone illustration will appear within your WhatsApp chat when a message has been played by the recipient. Another nifty feature: the volume of the recording automatically switches from speaker when held at arm’s length to soft when you bring it next to your ear.

WhatsApp has currently surpassed 300 million monthly active users (the total number of registered users is unknown) — with 20 million active users each in Germany, Mexico, India and Spain.

The service processes 31 billion messages per day, consisting of 11 billion sent messages from WhatsApp users and 20 billion messages received, up from the total of 27 billion messages it processed within a day in June.

WhatsApp told TNW in a statement that there will be more initiatives to come:

As WhatsApp continues to build an affordable, reliable global communication network, we will continue to find new and better ways for our customers to communicate quickly and efficiently with their friends and family.

➤ For more, head to AllThingsD

Headline image via abulhussain / Flickr