As stated above, I purchased an amtszusatz (rotary dial module) for my kleinen klappenschrank (small switchboard). Since I don't have a land telephone line, I had no way of using the amtszusatz and my switchboard as a PBX (private branch exchange) on our civilian telephone system.
After doing a lot of research, I discovered a Blue Tooth Cellular Gateway, produced by a company called X Link. You can check it out here:
http://www.myxlink.com/xlink_bt.aspx
It is a device that enables the user to connect land line telephones to up to three cell phones using Blue Tooth. Best of all, it supports rotary dial telephones! It costs less than $50.
It arrived today. Although the instructions suck, pairing the gateway to my cell phone's Blue Tooth was a piece of cake. I connected a modular telephone plug to one end of a length of military telephone cable, and on the other end of the cable, I crimped on spade terminals. I connected green to Lb and red to La on the top of the amtszusatz. I connected the modular plug to the socket in the back of the gateway.
It worked! I can now make and receive cell phone calls through my WW2 German switchboard.
When I get an incoming phone call on my cell, the amtszusatz buzzes and the little indicator door flops down. I press the lever down to the "Abfragen" position to answer via my operator's FF 33. When I am done talking, I move the lever to the center position and hit the "Trennen" button to disconnect the call.
To make a call, I move the lever down to "Abfragen." When I hear the dial tone on the operator's FF 33, I start dialing. The call goes through just fine. When done talking, I move the lever to the center position and hit the "Trennen" button to disconnect the call.
One thing I notice is that if I don't answer an incoming call just after the first ring, the amtszusatz hangs up. Gotta play around with it a bit more to see what's up with that.
The really cool thing about the Blue Tooth gateway is that it's powered by a 120 volt adapter that puts out 9 volts DC at up to 1 amp. So, theoretically, the gateway can be powered by a large capacity battery out in the field during, for example, a reenacting event.