writes: Google has sent out an email this morning that says in part: "Starting on June 27th, 2015, SMS notifications from Google Calendar will no longer be sent. SMS notifications launched before smartphones were available. Now, in a world with smartphones and notifications, you can get richer, more reliable experience on your mobile device, even offline."
You can find the announcement on Google's support pages as well
. "Richer" may be accurate, but I'm not sure that "more reliable" describes web-based notifications; that may be why the announcement linked does not apply for Google's "Work, Education and Government customers."