The new fibre-linked system is now up and running.  It is a little less flexible than previously in that a built in recording system for messages has been replaced by on-line voice mail.  This will cut in after seven rings and does not allow time for personalised messages, e.g. giving my mobile number.  In the event of the line being down for some reason it should automatically divert to my mobile.  The previous handsets do not work with the new system, but are digital and so should work with copper wire or if the base unit can be plugged in to a modem.  There are two pairs, one Binatone, one more modern Panasonic.  If you could make use of them just ask.