Bharat Sanchar Nigam Ltd has threatened to shut down its back haul microwave system, used for inter city-cellular calls, if the spectrum charges being paid by it are not brought at par with other cellular service providers.

BSNL, in a letter to the department of telecommunications, said the royalty charges for the spectrum were abnormally high.

"If the spectrum charges are not lowered further, we may be constrained to shut down most of the 2 Ghz (giga hertz), 6 Ghz and 7 Ghz links. Though the spectrum charges payable by us will come down drastically, the public will be affected as there will not be back-up microwave system any more," Prithipal Singh, Chairman and Managing Director, BSNL, said in his communication to the DoT.

The microwave system is used by cellular operators as a back up for inter-city calls. Though calls are normally carried on optical fibre cables, microwaves are used if the cables develop faults.

The government had exempted BSNL from paying for spectrum usage following its corporatisation. However, the exemption period expired in March 2003 and it was asked to start paying the charges.

Earlier, BSNL had asked the Wireless Planning and Co-ordination for a reduction in the spectrum fee. However, the subsequent modifications made by the WPC were not to the satisfaction of the telecom major.

Pointing out the anomaly in the WPC's formula, BSNL said for a 2-megabit link operating up to a distance of 5 km, it had to pay a royalty of Rs 144,000 against a possible annual revenue of Rs 55,000.

On the other hand, BSNL said other operators were being charged on a revenue-sharing basis.