Paying to use the Internet at a hotel has become synonymous with buying food on a flight: It's expensive and rarely comes free. 

That's according to the latest survey by PKF Hospitality Research which found U.S. hotels racked in $269 in telecommunications revenue per room in 2011, up 51% from 2009. 

The revenue likely came from Internet fees, said several analysts NBC News spoke with, no surprise given our near-dependence on Wi-Fi these days. What was once the domain of business travelers is now the bane of our existence, and even the most pragmatic travelers like streaming movies on their iPad or laptop. 

The trouble is hotels are reluctant to upgrade their service and investors are fine with that. But they have good reason: retrofitting can cost as much as $1.5 million for one building.

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[via NBC News]