A friend has just returned after going to see her UK family for Christmas and had a message on her answering machine asking her to call back. The message claimed, in French, that this was to avoid massive price increases and asked that she call 0899 96 76 72. Such calls cost €1.35 initially & then 0.34 per min. and they probably try to get you to hold on for as many minutes as possible.
Anybody wishing to know more could should simply Google 0899 France.