Hello,
Thank you for your answer.
I live in Poland, this is CYFRAL UNIFON TCL intercom - very popular in our country. But it is out of production now (building is from 2010). Today’s model is CYFRAL UNIFON SLIM.
In my opinion:
SW1 is switch under handset
SW2 is switch downstairs at the building
SW3 is button on my intercom to open the latch
I think, that the main unit in the building is TD3 or TD4, eventually TD6:
All diagrams you can find here:
Looking forward for info from you 
I can help in developing with this type of intercoms, if you have any questions or if I can check something - please let me know.
Regards,
Pawel