With an AE dial.
You can replace that dial with a WE 5H, and save the AE dial for use in one or another AE phone that came with some other dial.
The ringer box appears to be something other than WE; might also be AE (and can be replaced & saved ditto).
Note, these need proper subsets in order to function. Any WE subset with an induction coil or network block should be acceptable, though the local experts can advise on what's exactly correct for this model.