Much to the annoyance of its two bigger rivals, Bouygues Telecom has been given the go-ahead by Arcep, France’s telecoms regulator, to use its 1800MHz spectrum assets for 4G.

France Telecom and Vivendi’s SFR, number one and two respectively in the French mobile market, said Arcep’s decision hands an unfair advantage to third-positioned Bouygues. For its part, Arcep said the ruling should spur 4G network rollouts as competition increases.

And while the regulator noted that the big two can also apply to use 1800MHz spectrum for 4G, France Telecom and SFR maintain the new ruling effectively alters the value of the 2.6GHz and 800MHz frequencies they previously bid for.

SFR, reports Dow Jones, said that if the decision is implemented it would “substantially change the competitive and economic framework in which we made our [4G] bids”. SFR added that “the government and Arcep appear to have misunderstood the principle of legitimate expectations”.

Both France Telecom and SFR further make the argument that it’s easier for Bouygues to refarm 1800HMz for 4G because the third operator does not rely as heavily on that frequency for GSM as the country’s two bigger operators.

Bouygues made an application to Arcep last July in order to refarm part of its 1800MHz spectrum to operate a 4G service. Until now, 1800MHz in France has been restricted for GSM use. If certain conditions of relinquishing spectrum are met, Arcep says Bouygues can use 1800MHz for 4G from 1 October.

By that date, says Arcep, Bouygues must hand back 2.8MHz of spectrum in order to reduce its 1800MHz holdings to 2×23.8MHz (so it does not exceed the amount held by France Telecom and SFR in the country’s metropolitan areas).

By 25 May 2016, after giving more 1800MHz spectrum back, Bouygues should be left with 2x20MHz.

The regulator says that Free Mobile, France’s fourth operator – which doesn’t hold 1800MHz spectrum – may be allocated some 1800MHz frequencies if it requests them.

Bouygues has a legal deadline of one month to decide if it wants to continue with its 1800MHz request. The operator says it it will make its decision known within the next few days.