Arcep figures showed that the decline in mobile services revenue that started on the French market in mid-2011 continued throughout 2015, but that the rate of decrease remained on a downward trend.
Bouygues Telecom and Free Mobile are the first of France's four mobile operators to gain authorisation for 4G sites in the 700 MHz spectrum band.
Talks on a potential takeover of Bouygues Telecom by Orange are entering the home straight, although it still appears possible that a merger may not happen at all.
Iliad reported strong revenue and subscriber growth in 2015, as the enfant terrible of France's mobile market continued to be a thorn in the side of rivals with apparently unstoppable growth.
Orange refuted speculation that a deal to help it secure approval for a potential acquisition of rival Bouygues Telecom was imminent and said talks were still ongoing.
French billionaire and entrepreneur Xavier Niel reportedly approached UK regulator Ofcom to discuss a potential entry to the market by snapping up any mobile infrastructure CK Hutchison relinquishes in its bid to acquire O2 UK.
Arcep president Sebastien Soriano is closely following the progress of talks that could see Orange snap up Bouygues Telecom for about €10 billion ($10.9 billion), and warned that any deal must not harm competition in the sector.
Arcep asked French mobile operators to make specific plans for terminating network-sharing and national roaming agreements that have also been used to delay the construction of their own mobile networks.
After weeks of speculation, Orange and Bouygues Group confirmed they are in preliminary discussions over a possible merger between Orange and Bouygues Telecom.
Orange remained at the centre of takeover speculation this week amid continuing rumours that the France-based company is looking for acquisitions in its domestic market as well as in the wider European market.