The Thailand National Broadcasting and Telecommunications Commission (NBTC) plans to institute a new spectrum cap that would limit the total amount of mobile spectrum any mobile operator can have at 60 megahertz.

Significantly, the cap includes the 4G frequencies to be auctioned this year.

Should the cap be adopted, it would mean Total Access Communication (DTAC), owned by Telenor, the second-biggest Thai mobile operator, would be unable to bid for only small portions of the Long Term Evolution 4G spectrum.

DTAC, for example, already has licenses to use about 75 MHz, including 50 MHz of bandwidth in the 1800 MHz band, 25 Mhz of which is unused.

Operators with more than 60MHz of spectrum would be able to participate in the auctions but would need to return any amount over the limit to the regulator, the NBTC said.

The complication is that DTAC spectrum actually is not held by DTAC directly, but under a concession with state-owned CAT Telecom. DTAC naturally argues it should not be considered a license holder, subject to the 60-MHz cap, since its licenses actually are held by CAT.

But that is not unusual in the Thai mobile market.

Market leader AIS has just 32.5 MHz, and 17.5 MHz (900 MHz concession with TOT) expires in September 2015.

True Mobile holds 30MHz in the 2.1GHz and 850MHz bands and the 850MHz is a concession from CAT.