Steel Ericsson Model N2830
These phones were listed by Ericssons as being suitable for tropical use.They seem to have been used anywhere but the tropics. They were made in Sweden, at Beeston in Britain, and at Buffalo in the U.S.A. This one is a New Zealand Post Office phone built in Britain, although the New Zealand P.O. also sourced the phones from the other factories. It has the "sanitary" handset favoured by the NZPO. (That's the handset with the cover over the mouthpiece).
The round panel at the top is not for a dial fitting, but covers fuses and terminals.
There are three related models, all finished in the basic black. They turn
up at auction in the U.S. fairly often, and the price is quite reasonable for
a good example, but freight outside the U.S. is pretty high - they are, after
all, solid steel. The U.S. models can often be distinguished by an "Ericsson
- Buffalo" transfer below the bells.