This is the third time BSNL is approaching Trai asking them to review the decision. BSNL sources say that it would be difficult to implement Trai's order, as it would lead to a revenue loss to the tune of Rs 500 crore for the newly-formed corporate entity.

The issue dates back to January 26 when BSNL had introduced concessional tariffs for intra-circle calls ranging between 50 to 200 kms for its subscribers making STD calls almost as cheap as local calls.

The tariffs were reduced as much as to one-eighth with the pulse rate raised from 15 to 120 seconds for calls made over a distance of 50 km to 100 km. Pulse rate for calls made over a distance of 100-200 km was also raised from 15 to 30 seconds making calls cheaper by 50 per cent.

Cellular and other private basic operators made representations to Trai that BSNL should extend the benefit of lower call charges to those operators as well who use BSNL's infrastructure for making inter-network calls.

Trai issued a directive to BSNL stating that the revised tariffs must also apply to inter-network calls, i.e.; calls made from BSNL network to mobile network or to other private basic network. BSNL responded to the directive requesting the regulator to review its directions.