France's largest operator cites "divergence in deployment strategy" as the reason.
Orange is France's largest mobile operator, while Free is the brand name of Iliad group which was founded by the somewhat controversial billionaire Xavier Niel and has proved a disruptor in the French (and Italian) markets.
After the 5G spectrum auction in France that took place last October, Orange and Free had discussions about a mobile network-sharing agreement in France.
Quality and fibre
In a statement, Orange said, "Given a divergence in deployment strategy, Orange has decided to end these discussions.
"For Orange, the quality of its networks is a priority. Its mobile network in France was ranked best mobile network in France for the tenth consecutive year by [regulator] ARCEP.
"The Group is also fully committed to the deployment of fibre in France, providing two-thirds of the 24 million connectable homes that have already been built."
Last week Orange sold some of its rural fibre infrastructure, apparently as part of its strategy to speed fibre deployment.
Free/Iliad is yet to comment.