-Translation- AIS 0390/2003 December 22, 2003 Subject:The Upgrade of Ratings of ADVANC and its debentures To The President The Stock Exchange of Thailand Advanced Info Service Public Company Limited ("ADVANC") would like to inform you that the ratings of ADVANC and its debentures are upgraded from "AA-" to "AA" by TRIS Rating Company Limited (TRIS) and the details are as follow: Company Rating: Upgraded to AA from AA- Issue Ratings: AIS063A:Bt12,000 million senior debentures due 2006 Upgraded to AA from AA- AIS04NA:Bt5,000 million senior debentures due 2004 Upgraded to AA from AA- AIS06NA:Bt10,000 million senior debentures due 2006 Upgraded to AA from AA- AIS073A:Bt3,000 million senior debentures due 2007 Upgraded to AA from AA- AIS093A:Bt2,500 million senior debentures due 2009 Upgraded to AA from AA- AIS093B:Bt4,500 million senior debentures due 2009 Upgraded to AA from AA- AIS07OA:Bt5,000 million senior debentures due 2007 Upgraded to AA from AA- TRIS upgrades the ratings of ADVANC and its debentures from "AA-" to "AA". The ratings are based on ADVANC' s solid business position as Thailand's leading mobile phone operator with a very large customer base, and its continued strong operating performance and cash generation ability. The ratings also take into consideration ADVANC' s capable and professional management team, ADVANC' s well-recognized brands and ability to control expenses. However, these strengths are partially restrained by continuing intense competition in the mobile phone industry, especially after a new operator entered the market and the inherent technological risk exposed by all operators. ADVANC needs to be more cautious in paying dividend to shareholders when it creates higher debts to equip new technology. Please be informed accordingly. Yours sincerely, -Signed- Mr. Somprasong Boonyachai Director Advanced Info Service Public Company Limited Legal & Compliance Department Tel. 0-2299-5561