@Heliograph I believe it is an EB 67 Modell. I have repaired those.
Fun fact, the microphone and the loudspeaker was the same type. Open the phone by losening one screw and shake the phone a bit, switch the wires to the microphone and the loud speaker, you had to hold the hand sett upside down to use it.

@Smart58 I remember seeing handsets where the microphone and or speakers were hanging out of the handset 😁 slamming did its thing too