CAT Telecom's labour union has given the agency's board and management an ultimatum to accede to its demands before returning an unused five megahertz on the 1800-MHz spectrum to the telecom regulator to add spectrum bandwidth for the fourth-generation (4G) auction.
Otherwise, the union will take action against the management of the state telecom enterprise, said Sangvorn Phumtien, president of CAT's labour union.
He declined to elaborate on specific steps being taken or what measures would be implemented.
Mr Sangvorn said the union recently submitted its latest proposal to the board, with three conditions required before CAT returns the unused portion of bandwidth to the regulator.
First, the union wants the auction of an additional five MHz of bandwidth to be approved by the cabinet, not by CAT's board, because the board does not have the power to endorse a new auction plan.
Second, the auction must be split into two licences containing 15 MHz of bandwidth each, not three licences with 10 MHz each as requested by CAT concessionaire Total Access Communication Plc (DTAC). The sale of two licences is seen as enhancing the competitiveness of the bids.
Finally, the union wants the National Broadcasting and Telecommunications Commission (NBTC) to let CAT and DTAC jointly provide 4G LTE service or wireless public service on another unused 20 MHz of bandwidth until DTAC's concession expires in 2018.
DTAC has 50 MHz of the 1800-MHz frequency for voice service, plus 10 MHz of the analogue 850-MHz frequency bandwidth for data service. The company uses only 25 MHz of the 1800-MHz frequency.
Mr Sangvorn said the union agrees with the agency's proposal to return the unused portion of the bandwidth to the NBTC for the 4G auction, as it would be the most efficient way to eliminate the inefficiency and waste inherent in the block sizes.
"We [CAT's labour union] do not require any compensation or conditions attached from the government," he said. "But the return must either provide the maximum benefit to the 4G auction or create certain benefits for CAT's mobile business."
The NBTC had originally planned a November auction of two licences on the 1800-MHz spectrum containing 12.5 MHz each.
The 25 MHz of bandwidth is from True Move and Digital Phone Co, whose concessions with CAT Telecom expired in September 2013.
CAT and its 2G mobile concessionaire DTAC have jointly agreed to return to the NBTC a portion of five MHz of bandwidth from the unused 25 MHz on the 1800-MHz spectrum. DTAC's concession is scheduled to end in 2018.
The return would increase the bandwidth of each licence from 12.5 MHz to 15 MHz.