When was the last time you used one of these? While not usable these days, it looks good. Maybe you can call TelKom on your cell phone to get it back up and working?
Definitely some skill is needed here to avoid muggle attention. Perhaps just showing a keen interest in this relic.
Very small cache that deft hands can find. Tweezers may be of help, especially as the cache (hopefully) ages with more finds. Please replace log as best you can for future colleagues.
Cache on!