Vintage field telephone by The Spirit of St Louis.
With deep push buttons, on/off lever, stainless steel effect back plate and two carry handles. 
Tested and works on a UK network, I can’t guarantee this will work outside of the UK. No instruction leaflet so I’ve not tested the wider functions, but it dials well and rings clearly. 
In good vintage condition. Some signs of wear, little paint splashes etc, please see photos for more details. 
Dimensions: 
Width: 260mm (10 1/4”)
Depth: 220mm (8 5/8”)
Height: 100mm (4”)
Weight: 1.35kg