The first text messages were free and could only be sent between people on the same network, but in 1994 Vodafone – then one of only two mobile networks in the UK – launched a share price alert system. The arrival in 1995 of the Tegic (aka T9) system, which created "predictive" texting based on the letters you had typed, meant texting could take off.
Commercial services soon followed, and though they started life as a free service – because operators hadn't figured out how to charge for them – it was quickly realised there was money to be made from texting as the number rose dramatically. By February 2001 the UK was sending one billion texts a month, which at the standard 10p-a-text charge meant the business was raking in about £100m a month.
The amount of data in a text message is tiny, at just 128 bytes. Charged at the same price per byte, a 650MB music CD would cost more than £60,000."