A deal is expected to be completed by the end of the year, and it is intended that the agreement will help to reduce costs for both companies.
Other operators in Europe have embarked on a similar strategy, with Vodafone and Telefónica recently striking a similar agreement.
The French telecoms market has been subject to fierce competition among mobile players following the entrance of low cost operator Free 18 months ago.
The French government has also reportedly backed the agreement, said that network sharing in the market was suitable “when margin levels are more constrained”, according to a statement.
European competition regulators have opposed further consolidation in the market in recent years, but have seemed to be open to network sharing as a way for operators to reduce costs.