WhatsApp earlier this week tweeted it had processed 7 billion inbound messages, and another 11 billion outbound messages, which on equalling goes past the previous record for 10 billion messages, registered on August 10.

Apple's iMessage service is estimated to process over 1 billion messages per day. With increasing popularity of smartphones across the world, a lot of people have switched to IP-based messaging such as iMessage and BlackBerry Messenger. Services such as ChatOn, Line and WeChat are quite popular in Asia.

WhatsApp's 18 billion messages feat comes days after reports claimed the the company was in acquisition talks with Facebook. According to reports, the acquisition would help the social networking giant boost its mobile presence and push into more markets across the world. WhatsApp, however, rejected the reports, describing them as rumours and factually incorrect, while Facebook, released an updated Facebook Messenger for Android with WhatsApp-like functionality..