What cables are you using to connect the pstn unit to the telephone connection.

BT in its wisdom have chosen  their own standard on socket wiring, which is very different from the rest of the world! Bless BT 😉

The rj11 connector used by BT have the 2 phone wires connected to outside pins, pin 1 and 4 and the earth and bell signal to the two inner pins, 2 and 3 .

This is a source of issues when using UK phones abroad or visa versa .

Not sure what the B&O supplied cables in the UK are wired. I have US B&O set in the UK so knew what to do to make them work.

You might simply get it to work by avoiding UK type cable ( brought with you from UK) and use locally sourced cables. 

Regards

Peter 

Assuming the following:-

• You have ADSL filters (see picture below) connected to each phone outlet which has a phone connected and;
• The Beocom 6000 previously worked correctly and;
• You have tested the phone socket with another non Beocom phone

then the problem is almost certainly going to be the line driver in the phone exchange. No matter who the telecoms provided is, when they test the line they are almost certainly not going to find a problem because they just test the line for functionality, but the problem is normally lack of line current. The Beocom 6000 draws a little more line current than most phones. To under stand what I am talking about please review the thread HERE where this person in France had the line tested OK yet once the line driver was replaced it all worked.

A typical example of a microfilter is below