Help identify Siemens & Halske phone model

[Sergey Paganini]

In these first photos, this is what the device looked like when I bought it. Before he came from America to me.
As for mounting the microphone ear pad, it is attached with just two screws located 180 degrees opposite from each other.
In some other phone models, there is a mount with three screws spaced 120 degrees apart.
In this phone, the microphone mouthpiece is single, without rotating parts.