Hi

For quite a few years my fibre to copper landline phones have worked perfectly.  

I have an IPFire firewall router connected to my ONT and that is running perfectly.

My landline phones stopped working a week or so ago.  I can ring out, but I cannot receive phone calls.  The phones sometimes ring once, and then nothing.  No calls received.  This happens even when a phone is connected directly to the ONT.  That is without any connection at all to the house copper lines.  The symptoms are exactly the same if the ONT is connected to the home copper lines.  

I went to the spark help page and it talked about a dual plate.  I have a dual box next to my ONT, but never used it.   I don't know why it is there.  I have never needed to know.  I have just tried plugging a phone into the little white box on the right, and nothing.  No dial tone.  

The photo shows my ONT corner.  The landline has always been connected on the left end of the ONT.  Is this right?

Even with the phone connected directly to the ONT, the POTS LED is dark.

I have a nearby wall plate for connection into my home copper network.  I also have a need for a phone to be connected into that wall plate.  I have been using an old ADSL filter as a Y-splitter to connect the ONT to the wall plate and to the phone.  If you are thinking that is absolutely the wrong way to use a ADSL filter, you might be right, but it has always worked OK for me.  

Do I have my copper connections setup correctly or is there something obvious I have got wrong?  I have looked on the Spark website, but it is entirely unhelpful.