Many walkers carry a mobile phone with them and it can be very handy for booking accommodation ahead or calling a taxi, as well as for keeping in touch with people at home. Failing that, it is still possible to use public telephone boxes (although they get fewer each year), for which you need to buy a France Telecom card from a Tabac or Presse.
For all emergency services, ring 18 or 112.
Access to the internet is no problem in France if you are carrying a smart phone or something similar – almost every bar, hotel and camping ground has free Wifi. Otherwise, you can often get on the net at offices of tourism, public libraries (médiathèques) or cybercafés.
As for ourselves we do not take a phone or an internet device, despite the fact that it makes life difficult at times. We like the feeling of freedom and adventure that we get from being out of contact.