[AndiiT]

Hi again,
The N diagrams should show you where the wires need to be on the terminals inside the Planset and also on the extensions and ringing converter.

If your Planset has a Bell on/off switch it suggests that it may have originally been installed where there was an additional phone (Plan 1A or similar) or bell and may well have its connections strapped for an internal and not an external extension.

I haven't read back through your thread before posting this message, you are aware that if the external extensions aren't located a great distance away that the Earth connections can be a physical wire and not true earth aren't you?

Did you manage to obtain thermistors for the external extension bell circuit to prevent bell tinkle when dialling?

Regards

Andrew