To no one's surprise the gold standard on wireless substitution in the US, the NHIS, reports that the proportion of wireless only households keeps growing. As of July, 2011, it was 31.6%. That's a 1.9% increase since December of 2010 and translates into 30.2% of all US adults. Just eyeballing the graph below it does not appear that the slope of the line that matters the most to us--the blue line--is changing much. Hard to believe there are still people out there doing telephone research without calling cell phones.