I believe this is the Automatic Electric Hand Test Telephone that could have been used to secure a patent. The castings appear to be hand finished and the designations hand stamped on the body. The mouthpiece holes are slightly off indicating this is custom made and that they were drilled in later. I believe the dial could have been replaced but I believe the unit is complete.
The attached tag is dated several times with original signatures as it was processed. The oldest date date is Oct. 4, 23. The patent received date is Apr. 9, 1924. It shows the inventor as Hans Sangebuseh. In my opinion this is a one of a kind museum item.