Elvox 1/005 2p (1/019) replacement intercom

[PavanPal]

Hello everyone, 

I am living in the UK and have an apartment with an old non functioning Elvox intercom handset which I wish to replace. The number I can find on the device is 1/005 2p but after searching online and looking at other forums I believe the model is 1/019 The information I can gather regarding this model is sparse and I would like to ask for some guidance with the wiring of the device. 
I have attached some images of the already existing wiring and would appreciate clarity on what each terminal represents so I can wire accordingly to the new handset which I am yet to buy.

Any guidance will be appreciated,
Thank you