transitioned towards spectrum allocation by independent regulator. The 2007 constitution and the Act on Organization to Assign Radio Frequency and to Regulate the Broadcasting and Telecommunications Services include the provisions that a national independent regulator is established and frequencies for commercial activities must be allocated via auction. The first successful spectrum auction by the National Broadcasting and Telecommunications Commission was organised in 2012, allocating 45 MHz of IMT (2100) frequency band to three mobile phone operators. Legislation that governs the Mobile networks includes the Act on the Organisation to Assign Radio Frequency and to Regulate Broadcasting and Telecommunications Services 2010 (the NBTC Act) and the Telecommunications Business Act 2001 (the Telecommunications Business Act). Additionally, any operator wishing to issue telephone numbers shall obtain a separate licence from the NBTC, subject to a Telecommunications Numbering Plan issued by the NBTC. In 2015 the NBTC arranged two rounds of auctions for 1800 MHz and 900Mhz. In November, Advance Info Service and True Corporation won the 1800 MHz license in the auction which takes nearly 33 hours to complete. In December, True Corporation and Jasmine International won the 900 MHz auction. The significance of this auction is the establishment of Jasmine International in the telecommunication business which didn't have a new player for many years. There are many rumours following this auction questioning Jasmine International on its ability to pay the license fee to NBTC. In 2017, the number of mobile subscribers has reached 121.53 million, and in 2018 has already reached 125.6 million. To purchase a SIM card in Thailand, it is necessary to present an ID to register. At the end of 2021, the total number of mobile subscriptions in Thailand was 99.4 million, representing a mobile penetration rate of 150 percent of the total population. More than 96.5 percent of the total market share belongs to three large operators (including their subsidiaries): Advanced Info Service (AIS), 44.38 percent market share, Truemove, 32.44 percent and DTAC, 19.68 percent market share. Other operators include the state enterprises National Telecom (NT) with 3.45 percent market share, and mobile virtual network operators (MVNO) with 0.05 percent market share, resulting in a (HHI) of 3,421 On November 22, 2021, Telenor and Charoen Pokphand Group, officially announced they have agreed to explore a USD 8.6 billion merger plan between Thailand’s second and third largest telecom operators (by subscribers), True Corporation (TRUE) and Total Access Communication (DTAC)