Any fault such as noise on your line will affect how your broadband works but from what you describe I believe that the problem is a faulty ADSL filter.
These filters are used to separate voice and broadband data signals.
They are used for all dégroupage partiel (when a customer stays with Orange, formerly France Télécom, the historic operator) for their fixed-line telephone subscription but chooses a competing operator for their internet connection and television) and those dégroupage total (when fixed line and internet and television services are moved away from Orange) services that use the old T-shaped phone sockets.
More recent installations use a DTI box, which has a socket for the broadband connection and does not use a filter as all calls go over the internet service.
ADSL filters are small devices that you plug both your modem and telephone into, with the other end being plugged into your phone socket.
They have no warning lights and no moving parts and sit in the background.
As there is no visible indication if they have stopped working they are often forgotten. However, it is simple to test if this is where your problem lies.
You can either carry out the quick and simple test below or ask your telephone company if they can help identify the fault.
All you need to do is remove the ADSL filter from the telephone socket and connect your telephone directly to it. If the calls you now make are crystal clear then the filter is faulty.
Replacements can be purchased at electronic shops or in big supermarkets such as Leclerc or Auchan and cost approximately 8€.
Alternatively search online for an ADSL filter.
Question answered by Bob Elliott from the telephone and broadband provider, UK Telecom. See uktelecom.net for more information on their services in France. If you have a query on this topic send it to email@example.com