Over-The-Top (OTT) messaging apps such as WhatsApp, Viber and Apple iMessage generated an average of 19.1 billion messages per day in 2012, and are expected to hit 41 billion messages per day by the end of 2013.

According to research company Informa, the 2012 figure outstrips the 17.6 billion SMS messages sent each day, and the figure forecast for in 2013 is more than double that expected for SMS.

There were around 586.3 million OTT messaging app users in 2012, with each user sending an average of 32.6 messages per day via their app, six times as many messages as SMS users.

Informa senior analyst Pamela Clark-Dickson said internet-based messaging is increasingly being used as a substitute for SMS in some markets and is having “a significant impact” on operator traffic and revenue in Spain, the Netherlands and South Korea.

In response to competition from these apps, mobile operators France Telecom-Orange and Telefonica have respectively launched the Libon and TuMe messaging apps.

Reflecting the increased interest in messaging apps, Nokia recently launched the low-cost Asha 210 phone featuring a dedicated WhatsApp button.