AE210
The intermediate station can talk to one or the other line, depending on whether the switcher is placed on the left or right. A signal coming from either line rings the bell of the intermediate station, regardless of whether the changer is on the left or right. Both lines can signal and talk to each other, if the intermediate station's microphone is on. When two devices talk to each other, the third cannot listen.

The telephone consists of:
Frame of black lacquered iron sheet.
Horizontal microphone RE 1024 with telephone cord RS 6003, wall mount cable RS 9636 and wall mount.
Four-magnet generator RH 4451.
Ringer with 1000 ohm resistance.
Two-way switch.  Fitted on lower front of case.
Connection clamps, which are built-in.

Overall dimensions: 13.1 x 7.6 x 5.6 inches.

Weight 11.46 lbs.

Taken from the L. M. Ericsson Telephones and Signalling Material Catalogue No. 122 (1930) - Swedish translation