The Council of State ruled on Friday that all previous amendments to mobile-phone concessions run counter to the 1992 Public-Private Joint Venture Act.

The Information and Communication Technology Ministry may thus have all private cellular concessionaires amend their concession contracts in line with the Act and adjust the share of their revenue paid to state concession owners TOT or CAT Telecom to a uniform 30 per cent.

The ministry will set up a committee to negotiate with the cellular operators. Whether adjustment occurs will depend on the outcome of these negotiations.

Advanced Info Service (AIS), Total Access Communication (DTAC) and True Move each share 24-25 per cent of revenue with TOT or CAT. AIS has over 20 million subscribers, DTAC 12 million and True Move around eight million.

According to one foreign brokerage house, if DTAC has to pay an additional 5 per cent, its 2007 earnings could drop 25 per cent, resulting in a decline of its estimated net profit to Bt5.796 billion. DTAC was expected to post a net profit of Bt7.72 billion this year.

AIS has had two key amendments to its concession, an extension of the concession from 2010 to 2015 and a reduction in prepaid concession fees from 30 per cent to a flat rate of 20 per cent. If the ICT ministry decides to bring its prepaid revenue share back to the original 30 per cent, it will cut AIS' earning by 12 per cent in 2007, resulting in a decline of estimated net profit to Bt16.63 billion.

However, the analyst's projection for AIS does not included its interconnection revenue, since unlike the other cellular operators, AIS has decided not to record such revenue until the legal issues surrounding the interconnection charge are sorted out. AIS is expected to have net interconnection revenue of Bt3 billion in 2007 and Bt2.4 billion in 2008.

The interconnection charge introduced by the National Telecommunications Commission last year mandated all telecom operators to share voice and data revenue between the networks involved in the calls.

DTAC is estimated to have saved Bt514 million in the first quarter after stopping the payment of the access charge to TOT and adopting the interconnection regime instead. The access charge is the cost all cellular operators which hold CAT concessions have paid TOT for accessing other networks through TOT.