I'm actually using a Neo2 postpaid contract from Bouygues Telecom.
Bouygues Telecom : téléphone mobile pas cher, forfait Neo et carte Bouygues Telecom
It includes unlimited data, unlimited calls + unlimited messaging to France some hours a day (you have to choose which ones).
Calls to Europe are at the same price as the national ones, with per second debiting method, and are included in the bundle.
Costs when the bundle is finished, calls to France and Germany cost 38 cents a minute.