A revolutionary form of communication is in decline - just 20 years after it changed the way that people interact with each other, The Guardian reported.

Used by four billion people around the world, the SMS (Short Message Service) took the world by storm after its birth in December 1992.

But after two decades of fervently bashing keypads with our thumbs, media watchdog Ofcom has reported a decline in the volume of texts sent.

The number of text messages sent in Britain peaked at 39.7billion at the end of last year, but is now down to 38.5billion, following two quarterly declines.

The fall has been attributed to new forms of communication which have taken over from the basic SMS system.

Owners of modern smartphones now have a plethora of ways of communicating with each other - including Tweeting and instant messaging.

The first ever text - sent in December 1992 - simply read 'Merry Christmas', after being sent by engineer Neil Papworth from his personal computer to Vodafone's Richard Jarvis.

This humble beginning kicked off a cultural and social revolution in the developed world, and texts have been used to seal business deals and even convey marriage proposals.