Something important has happened: the volume of SMS text messages sent across UK mobile networks has declined for the first time ever, Ofcom has reported.

The regulator's figures show that during 2012 volumes fell to 39.1 billion and then 38.5 billion in quarters one and two, which means that the official peak will probably now be recorded as being the last quarter of 2011 when the number of texts sent reached 39.4 billion.

To put this into perspective, as recently as 2006 the volume of texts sent in the whole of that year was 51 billion, a third as of 2011's total. The sudden levelling off in the last year suggests the medium's years of growth and pperhaps dominance are now behind it.

It's a small decline, but it is a decline nevertheless. After a decade when it benefitted from being the easiest and cheapest medium for mobile communications, it is now being slowly usurped by social media, smartphones and tablets.

Texting remains hugely popular among some groups, principally young teens, who send an average of 193 texts per week. This is, Ofcom said, double the level of a year ago, which could be caused by the universal bundling of unlimited texts in most phone packages.

Hyper-social older girls remain the medium's most avid users, sending 221 texts per week compared to the 164 sent by boys of the same age. Even youngsters in the 8-11 age group sent a surprising 41 texts per week.

SMS texting began in the UK so perhaps it's fitting that its first important epitaph should be written by the country's consumers.

As has become tech lore, the first ever SMS was sent exactly 20 years ago today - 3 December 1992 - by Sema Group engineer Neil Papworth, to a (by today's standards huge) Orbitel 901 mobile handset.

Received by Vodafone's Richard Jarvis, the message read "Merry Christmas," which considerably under-utilised the available 160 character length. No reply was possible; the first two-way SMS services were eventually offered to the public in Finland two years later.

'When texting was first conceived many saw it as nothing more than a niche service," commented Ofcom's director of research, James Thickett.

"For the first time in the history of mobile phones, SMS volumes are showing signs of decline. However the availability of a wider range of communications tools like instant messaging and social networking sites, mean that people might be sending fewer SMS messages, but they are 'texting' more than ever before."

Today the once-simple joy of texting has an image problem. It is as likely to seen as the medium for cyberbullying, text spam, toll cyberfraud and pointless non-communication as a liberating force in which human beings tell their significant other that they "might be late home from the pub."

Texting will be with us for years to come but perhaps, like email before it, it has started its slow journey to 'legacy' status.