Ericsson type 1951 Questions

[Matilo Telephones]

As for the paper label at the bottom: it was put there by the CWP, where these phones were refurbished. It is a quality control label, and contr means controleur > quality control inspector.

And CWP stands for what? Czech Wiring People?

:-) Almost.
It stand for Centrale Werkplaats PTT, Central Workshop PTT. It was their main technical facility where they did repairs, refurbishment and even production of equipment.

The building is still there, but has been converted for other uses: https://nl.wikipedia.org/wiki/BINK36

[Matilo Telephones]

I like the sounds of these too, same with the Heemaf 1955, which you have shown in your picture too.  The internals and I believe the bells are the same between these phones.  The PTT specified the internals in the norm.

They sound a little bit brighter than a 302.

Is there a manufacturing year on the Heemaf?

I'm not quite sure about the specs on the bells in the Norm 51. I'd really love to read that Norm 51, but as yet I do not have anything with regards to the actual contents.

The bells on Dutch phones (and many other European telephones) have a half note difference.

Bells on Norm 51 phones do differ in size and note. The Heemaf 55 even has 2 variants, one with small bells (these are lower and flatter) and bigger ones, a little higher than the other.

By the way, Fabius' telephone has chrome (or nickel plated) bells. That is quite uncommon. Most of them have black bells.

I have a hunch that these are early versions, but have not been able to find confirmation of that.
The DBH15 on which the type 51 is based had unpainted bells.

Is there a date on the capacitor, Fabius?