Happy bday! SMS txt msgs turn 20

It took SMS several years to take off -- and for some of that time, Papworth didn't have a cellphone.

"It took me a long time to get a cellphone. But I remember, I went to the Ideal Home Exhibition in London and Vodafone had an offer so I finally bought one," he said. "Back then, I didn't think I needed one. I only got a few calls a day."

The introduction of prepaid cellular service and innovations like T9 predictive text input helped the market grow and in 2000 the industry counted 17 billion text messages, according to data from Ericsson. That number grew by around 20 times over just the next two years.

It's estimated that there are around 6 billion cellphone subscribers today and almost all of them have access to SMS.

"The market is almost saturated, but it continues to grow with the growth of the planet," said JF Sullivan, chief marketing officer at Acision. The U.K. based company accounts for about a third of the SMS messaging system market and customers include the likes of Vodafone, Telefonica, Telia Sonera and Sprint.

"Everyone continues to use SMS and it doesn't look like it's dropping off anytime in the future," he said.

Part of the success of SMS -- perhaps its key to success -- is its universal availability.

"You can still get to everyone," said Sullivan. "All of those people holding a handset can be reached."

Looking back on the last 20 years since he sent that first message, Papworth says he's not surprised at how successful SMS has become.

"At the time, I never thought it would be so big," he said. "Now I see what it has become, I'm not surprised because it's so easy. It's on all phones. Not everyone has a smartphone and GSM is still rolling out in some countries. In those countries, not all customers will have a smartphone, but at least everyone will have a basic phone."

Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com