I have a small collection of Ericofons. Most of them worked for placing a call, and could receive a call – but the buzzer didn't buzz on an incoming call, so they could only be used as secondary phones where there was another phone that rang.
The explanation often given on ebay is that they were intended as extension phones for the bedroom. Maybe the idea is that you can hear the other main phone ring and can answer on your Ericofon if you want, but on the other hand without a phone buzzing right next to you, you can ignore it and go back to sleep if you want?
Anyway, I wanted mine to buzz. So I looked around on the Internet. This excellent website: www.ericofon.com had a page that sounded good: Wiring The K4 or K14 Swedish Made Australian Chassis but I think it's for re-wiring an Australian phone to work on the North American system. I have no idea if that is compatible with the Australian system.
Then I bought an Ericofon from a very helpful Australian ebay seller who also included a phone cord and a note explaining that the secret to making the buzzer ring was all in the connecting cord. This cord made the buzzer of most of my Ericofons work. Here's a photo of it:
I should point out that I don't know about wiring. I cannot read a circuit diagramme. I'm also somewhat concerned that each of the three Ericofons I've opened up had slightly different wiring inside.
So, it may be wise to get this checked by someone who does know what they are doing. Otherwise, use this at your own risk and don't blame me if your phone blows up or your house burns down!
I'm just showing you a photo of the cord I was sent that made the buzzer in my phones work.
Note that the cord I was sent is a 2 wire version. Most cords in the shops now seem to be 4 wire. You could presumably use a 4 wire and just disconnect the 2 outer wires – but note that the 2 inner wires are inverted. I mean, the green and red have swapped places as compared to the 2 wire version.
Also, annoyingly, some of the cords you can buy omit the middle two connectors in the socket:
If you can read circuit diagrammes, this fellow seems to know a lot more about things: Australian Ericofon Installation & Wiring
to Terios' other web pages