Margin compression is a reality of the global telecom business, and has been since voice revenues peaked in the United States either 2000 or 2001, and peaked globally a few years after that. For a time, the logical supplier response is to try and sell more units at lower prices. That can last only so long, however.
Text messaging has seen the same trend. Volume might be up. In some cases revenue is up. But profit margins are compressing.
Internet access bandwidth consumption likewise has followed a similar trend. Bandwidth prices on undersea routes continue to fall.