There are certainly not enough vacuum tubes to implement a computer. Perhaps a simple UART (shift registers) and associated analog circuitry (modulator/demodulator). Would they have given a name to such units? Or does "Dumbkopf I" refer to the computer to which it was connected? The test panel seems to imply it can generate an interrupt and the BNC or RCA jacks might have been for audio in/out.
MIT did work on prototype and research/development of SAGE, which would have required remote communication. I guess it could have also been a more-generic unit that was used/reused for many different applications.
I'm guessing there is no longer anyone that remembers, or documentation that explains, the naming conventions. There is a SAGE computer at the Smithsonian, or at least there was one donated there. I was fortunate enough to tour the SAGE facility in WA back in the mid-70's, while it was still in operation. Certainly, the military would not have used such naming conventions. A fascinating era in computing, though.