What from this box? Signal corp us army

[matiash]

Hi Guys!
Find this box
it s unusual for our area
what is this?

[ruddersrangers44]

Some sort of radio/headset/field phone equipment.other than that i'm clueless.

[satchiel]

In its day, it would have housed a radio test set, which would have looked similar to the below, which is a another variant (I-56-C):



A bit more info:

I-56 - RadioNerds