eMarketer.com notes that 7.47 trillion text messages were sent worldwide last year via short message service or SMS. This is up from 761 billion in 2004 but down from 7.7 trillion in 2012.
What is supplanting them is over-the-top or OTT mobile messaging services which are done using services provided by companies like Facebook and Google rather than cell phone companies.
Last year, about 10 trillion OTT messages were sent. eMarkter estimates that by 2018 there will be 67 trillion of these messages sent and that traditional text messages will fall to 6.3 trillion.