I do not know much about this phone, so is it Ericsson made or some Finnish made. Anyway many Ericsson phone parts are used.
The phone has been used as public telephone in Hotel National in Turku. The reception has connected the ordered call to this phone in the hotel entrance hall. Hotel has been in operation from 1925 up to 73 and the hole hause is pulled down in the beginning of 1990.
The coins what the phone uses "nikkel mark" is used from 1928 up to 1964. Older ones made from nickel but during the war from copper and steel.