The study found that in Q3 of this year, cellphone owners sent an average of 678 texts a month, down from 696 texts a month in the previous quarter.
Though that’s a small dip, the change is noteworthy because for several years, text messaging had been steadily growing in the United States. Mr. Sharma said it was too early to tell whether the decline here would continue, but he noted that Internet-based messaging services, like Facebook messaging and Apple’s iMessage, had been chomping away at SMS usage. He said the decline would become more pronounced as more people buy smartphones. A bit more than 50 percent of cellphone owners here have smartphones.