In the 36 hours or so since AT&T and Deutsche Telekom announced that the American carrier would be buying the U. S. subsidiary of the German phone company, there has been plenty of speculation (some of it right here) about what this will mean for customers and the wireless industry, but not very much, frankly, about why T-Mobile is worth $39 billion to AT&T. It’s about more subscribers, we’re told as though that is obvious, and back-office savings, plus extra spectrum with some special plans for 4G, but that’s not the biggest reason at all. The biggest reason why AT&T wants T-Mobile is because of WiFi.

Subscribers are nice, as are back-office and marketing savings, but […]