The telecom regulator has reiterated the winner of August's 1800-megahertz spectrum auction will be able to freely reshuffle the spectrum acquired with other operators' 1800MHz slots.
The scheme could entice Advanced Info Service (AIS) to enter the auction to exchange the new slot with True Move, which would result in more efficient frequency management for the country's largest operator.
Takorn Tantasith, secretary-general of the National Broadcasting and Telecommunications Commission (NBTC), said in 2015 two licences were auctioned on the 1800MHz spectrum, each containing 30MHz of bandwidth.
True Move won the first slot between 1710-1725MHz for upload and 1805-1820MHz for download, while AIS won the second slot of 1725-1740MHz for upload and 1820-1835MHz for download.
The 1800MHz auction scheduled for Aug 4 is for three licences adjacent to the 2015 auction, as shown in the graphic.
"Spectrum allocated on the same frequency over different periods bring advantages and disadvantages to operators. The NBTC is allowing the winner of August's 1800MHz licence to negotiate with other operators to change their spectrum slots," he said.
Mr Takorn said although the NBTC's auction design was for three licences, only one licence is to be bid on after True Move sent a letter to the Stock Exchange of Thailand that it will sit out the auction.
That would leave only two prospective bidders, AIS and Total Access Communication (DTAC).
"Under the N-1 rule in the auction's conditions, the NBTC can auction only one licence because there are not more than two prospective bidders for the auction," said Mr Takorn.
The rule states the number of qualified bidders must be more than the number of licences to be auctioned.
If there is only one qualified bidder, the auction will be extended for another 30 days to open for more prospective bidders. Beyond the 30 days, the licence will be auctioned for one qualified bidder, allowing the bidder to bid once.
The NBTC will reserve the two licence slots for the next auction, which is expected require least 1-2 years to prepare for.
Mr Takorn said the NBTC set to auction the licence for 740-1755MHz for upload and 1835-1850MHz for download.
He said selecting the license is strategic on the part of the NBTC as it is the most adjacent slot to the 1800-MHz slots given out in the 2015 auction. The NBTC is also encouraging AIS to join the auction for technical reasons, because the license's slot is adjacent to AIS's present 1800-MHz slot. The auction will be more competitive if AIS joins the bidding.
Mr Takorn said if AIS grabs the licence, True may need to reshuffle its existing 1800MHz slot with the new licence because True may need to ensure that is will not need to enter future auctions because of technical constraints in network management.
If AIS wins and True does not ask for a spectrum slot reshuffle, True must win a licence in the next auction, which will allow the company to better manage spectrum.
DTAC, by contrast, has no option because it failed to win a licence in the 2015 auction, he said.
If DTAC does not join the auction, the expiration of its 850-MHz and 1800-MHz 2G concessions on Sept 30 will shut down its 2G services, and negatively affect its 3G and 4G services.