After the German Bundespost discontinued the "Tischmünzer (http://www.classicrotaryphones.com/forum/index.php?topic=24631.0)" in the early 1970ies, it took over 10 years until new private pay stations became available.
In the meantime innkeepers, hostels and other semi-public operations had to install a tariff unit meter and charge customers manually.
The new payphones were named "Clubtelefon" and appeared 1987 for rental, later also for purchase by the subscriber.
The Clubtelefon 41 was the last pay station issued 2001-2008 by Telekom, the successor of the Bundespost after privatization. It was made in Spain by Siemens Elasa. The coin validator was made by Azkoyen, a Spanish manufacturer of vending machines. The coin validation can be set to Deutsche Mark or Euro.
I found the phone on eBay, it is still showing name and number of the previous owner: A fishing club in the Black Forest. Apparently it was installed in the club home.
The introduction of the Euro currency in January 2002 initiated a last short boom for new payphones, as most oft the older ones would not accept the new coins! Like the fishing club, many places still felt an obligation to provide a phone, while mobiles already had taken over, but not fully. Mobile fees were high but soon dropped. I doubt the investment of the Clubtelefon was profitable.
The 41 is not armed and only for supervised areas. The similar model 11 would have an armed cord, but still a plastic front. The fee is charged per tariff unit. Telekom would provide a 16 kHz tariff unit pulse, the time per unit would depend on the time of day and if it was a local, regional or long distance call.
There is a menu to set the charge per unit. Alternatively, there's an option to define own time periods . After the the "official" tariff pulses are no longer provided, this would be the only option to operate the payphone today.
The phone did not clean up too well yet. The display window is scratched and I'm looking for a way to clean the inside. It seems to be a quite soft material, getting scratched easily.