Hi,
you should unplug anything that is plugged into a phone socket, including the filters. then just try the phone and modem/hub into one socket together via a filter.
if still does not work, then try a different filter. There is no reason at all why it should not work unless the filter is faulty or the phone. make sure you un-plug everything else, including sky box if its plugged into the phone socket. ring tripping is caused by either a short circuit or a " battery fault" which means your outside line is in contact with some one elses.
Let me know the outcome.
regards,
annie.