In case of total unbundling, the lines are directed without filtering directly to the service providers, which supplies the globality of communication services to their customers (sometimes even a switched telephony service). In this case, the service provider is the only point of contact for the customer, even in case of physical problems to all “classical” phone equipment (fax, modem, telephones) in order that they do not disturb (and possibly are not disturbed by) the ADSL traffic. The ADSL modem or gateway itself is equipped with an internal high-pass filter which enables subscribers to be connected directly on the phone line.