The earliest catalogue I could find with this model was from 1921. This model clearly shows the rise of semi-automatic and automatic telephony. CB telephony made the use of a generator unnecessary and this model is basically a CB telephone with a dial bolted on as a separate unit. They were produced with and without dials and could be upgraded in the field to automatic telephony easily.
Typical for Swedish telephones from this period is that some components are mounted on the underside and others at the top of the base.