Unidentified Dutch PTT Headset (with no microphone)

[Budavox]

Hello all, I came across this device on a local marketplace.
It has the Dutch PTT logo on it, I assumed this device is related to telephone.

There are numbers 1-4 on the dial with 0 in between them.
The headset also has no microphone, so it is only used for listening.
It seems also this device would be attached to a vertical surface like a wall and secured by screws.

Does anyone have any idea what this is..?

[TelePlay]

If I were to guess, I'd say a 4 line secretive listening/monitoring device.

Does that twisted braid coming out of the back have 5 conductors?

I'd think the "0" positions were off/muting positions.

Did you look inside the "rotary" switch to see what components, if any, are behind the rotary dial.

Could be telephonic (two way) or radio (monitor outgoing transmissions) related.

European members would know best.

[TelePlay]

There is one for sale on eBay right now for $39 plus $18 shipping from Greece.

https://www.ebay.com/itm/175641951129

No headset included but the connector at the bottom is interesting.


Seller's description shows he doesn't have a clue as to what this is:

"Dimensions: 12 x 9 cm -- Condition: Very good, as seen. -- Everything as seen in pictures. -- Please see pictures for details or just ask me for more! -- Shipping to: Europe 16 USD, to USA and everywhere else: 18 USD. Wait for my invoice! -- COMBINED SHIPPING! -- Antique PTT Wire Broadcaster Selector  Philips. -- DIAL Numbers Telephone Radio"

I wonder what happens if this is plugged into a 115/120 VAC outlet and the wires inside the housing are present?

[countryman]

If it was used in Europe, there would be no mains sockets where it might fit into. Luckily 
Apparently the prongs go to some sort of induction coil? In Budavox' picture the headphone is connected in that place and there seem to be 5 wires on the other side. That would make sense for a 4 position switch.  In the eBay pic there are much more wires cut flush. Great condition, as described, yes.
I have no clue what it was used for...

[tubaman]

There's a variation here - https://drouot.com/en/l/16275020-un-interrupteur-radio-de-distr - where it's described as a radio distribution switch. Used like that the pins on the bottom would be the input from the main radio and you could then switch the output to speakers in different rooms. Used in schools perhaps?

[Budavox]

I wonder what happens if this is plugged into a 115/120 VAC outlet and the wires inside the housing are present?

I will ask the seller whether they would let me see the inside.. this could give us a clue.

In the tubaman's product, the extra speakers could be the substitution of the headset.. so the device would act as an audio out.
There is an extra dial under the switch.. maybe for volume control (?)

I think that this device could be a radio source selector is true (since the listings that tubaman and TelePlay posted contain 'radio')
Maybe there was a job in the past where you need to listen to some audio sources that you can switch, or this device could be put in a room; so you can change the music that broadcasted through speakers using the device..