There is one in Berlin named Funkloch. Literally translates as radio hole, meaning an area where you can't get a signal. There's a pun in there too in that Lokal means pub, so you can read it as Funk Pub.
This tweet confirms there's a bar with smartphone ban in Weißensee: https://twitter.com/ennopark/status/567272387293761537
Only other "Funkloch" I found in Berlin is a youth center, so the above result is very likely the right one.