Telecom Line Adaptor
RJ45 Plug to UK Telephone Socket (Extension)
To enable telecoms and other communications equipment to be used
on RJ45 CAT5E and CAT6 structured wiring systems
that are now commonly used in home and offices.
The BT4503 is a secondary adaptor and has no electronic components embedded.
Just simple plug to socket adaptor.
The BT4504 is known as a PABX master and is the most common type used in industry.
It incorporates a bell ringing capacitor as required by some networks.
The BT4505 is known as a PSTN master and it incorporates a bell ringing capacitor
as required by some networks and a surge arrestor to help prevent the fallout from lighting strikes etc.