Are you trying to better Beethoven?
I have to state, that I am a sharp critic of such experiments, "playing around". Doing it by oneself in private to learn is one thing, promoting it in public is another. These instruments were for the time highly developed, finely tuned technology, and worked just perfectly in conditions or situation that were technically very challenging. IMHO, it is often quite a bit of a challenge to make them work today the way they were intended to work even without challenging conditions, such as 100 miles of copper wire, ground shorts from wind, ice, and rain. For example, how many collectors do you know who actually built a properly functioning party line with their phones, whether it is used frequency ringing, polarized ringing, or anything else more sophisticated than a dry magneto line?
Most here probably know exactly how to cobble together a somewhat working telephone from spare parts, working at least under the exact condition during the experiment.... a handset, an induction coil, or even just a resistor and and a capacitor. That's a nice little exercise. But I don't need to tear into a nice, complete instruments like this to confirm that. We know how a handset sounds and speaks. Connecting a battery to the ringer for a test is nice exercise, because ringers don't all sound alike.
But starting to insert components into this circuit to somehow try to get sounds in and out of this box cannot duplicate the experience of authentic operation and one can achieve that by disconnecting the handset set and hooking it up to a working modern phone. There is even enough room in that box to put a 101A induction coil between the line and the handset. But what is the point of that?
Ok, this is why I suggested to buy the second phone, a second phone is needed to demonstrate this technology, at least the speaking part. Signaling is still another story.
