This is a piece of early telephone history. Siemens designed the first of the 200 series telephones and here is one of the first made.
As you can see, the cradle was quite different in the very early days and and soon redesigned, probably due to the ease this one can be broken, due to the sharp changes in the thickness which were changed to smooth curves on the later design. Note the body has a brass insert moulded into the Bakelite to hold the dial. This was probably difficult to mould and was redesigned, changing to an all Bakelite model, very soon into production.
The internals are interesting as you can see they were cast in metal with insulation to prevent shorting out on the metal. Again soon redesigned in Bakelite for mass production and better performance. Another interesting feature is that the base is made of cast metal and dated 1929. I have seen these dated up to 1932 and so they may have continued to use this base for a while. Note the GPO No10 dial marked Siemens 1929 with its original enamel dial face and solid copper finger dial, with small dial label holder. This was probably one of the very first low production models made in 1929-30. This one has what I think is the original handset cord, which is quite remarkable. I have kept the original feet, as although perished to some degree, are original. I believe this is a museum piece and will end up in a top collector's possession.
This model was designed to be fitted to a GPO No1 wooden wall mounted bellbox. Far more interesting and rare than any Bakelite coloured telephone. This is a collector's piece and so not working. There is no reason why this would not work if wired to a GPO No1 bellbox. If his is what you want me to do for you, then contact me and I will quote to find one and wire it up for full working condition.