This is an early DeVeau 6 button desk set.  It has a smaller base than the traditional, later models and a slightly different transmitter mount. Marked transmitter and base.  "Solid" receiver.  The scan is from an original ad in the 1902 issue of Electrical World & Engineer magazine, showing this telephone. The later, larger models of this DeVeau desk set are more common, but this early, smaller version is very rare.