a puzzle with Soviet 6N1 and German sticker inside

Hello,
I found this Soviet radio in Eastern Poland - 6N1. It had to be bought between 1939 and 1941 and produced between 1938 and 1941. This would not be unsual, but
(1) using and possessing of radios in Poland was that time illegal as per German law
(2) the radio has a German sticker inside (please see the picture)
Does anyone have an idea what it means? Has anyone seen a sticker like that on any (other) radio?
Any hints appreciated.

I did a search for most of those words. Electron I am assuming deals with electronics. The Bialystok is the largest city in Poland. The Fernruf means phone number and Schloss is probably a street so I am thinking it a building number. Its probably a sticker so if a person has trouble they can call that repair shop. Like the ones you sometimes see on oldar radios the shop put on here in the US.

Thanks for your interest and help. When the radio was bought (before 1941) Bialystok was occupied by the Soviets, and not Germans. The Germans came to Bialystok in June 1941. So if this is a repair shop's sticker, it was put there after '41, and it means that the radio was owned by a so-called Volksdeutsche (as I said, others were not allowed to posses and use radios), very interesting considering the history of Eastern Poland.