Another update:
This is a Turkish Payphone and not a German one. The fellow I bought it from sent more information on it and fellow member Jeff Lamp also did some digging.
Sellers information:
Regarding the orange phone, I was told that we got it from Germany and it was used as part of the Glines program in the early 90s. But at that time Nortel had a joint venture in Turkey called Netas. Netas was tasked with the development of DMS100 switches for the international market. But the Netas software deployed on the DMS hardware only supported POTS features. So in the late 80s and early 90s Nortel started selling its own international version of DMS100 software (I worked on this project). We used the orange payphone as part of Nortel's international DMS program.
Like I said I was told we got it from Germany, but it is possible that we got it from our Joint Venture partner in Turkey (there were a lot of exchanges going on back then).
Jeff Lamb:
Jeff spotted the word "Teletas" on Google, which was either the Turkish Telephone company or a Turkish telephone manufacturer.
He incorporated that word in his queries, and went through everything and got a little closer. He finally queried "images of payphones used by TELETAS in Turkey", and that's when he said everything started to show up.
Jeff also found information on Abloy locks.
Abloy locks : the company is very secretive with their product. The isn't much printed about their locks, and even less of diagrams showing the locks in and exploded view. The lock function on that payphone should be what's called a "cam lock". The words "cam lock" don't refer to the way the actual lock itself operates, as Abloy are a disc lock, but it describes how the lock, locks whatever it's installed on. It could be a lever that's made to hook a pin inside the payphone, or it could be a simple flat bar that swings into place and blocks something that prevents the housing from opening. It may be another type, but cam lock is the most logical.
By the way, Abloy locks aren't "pickable", or at least I've never run into a locksmith who claims to have picked one.
I had also contacted Abloy and got no where with that. I was told there is no information available.
The pictures are from a google search. Turkish Payphone and the tokens they use.