Thailand's DTAC yesterday launched 3G services, despite threats from concession owner CAT to sue for breach of contract.
DTAC is now offering 3G services in Bangkok, at no extra charge to existing data plan subscribers.
But CAT Telecom insists that DTAC has no authority to offer 3G, and pending legal consultation plans to send a letter giving the operator 90 days to stop or face arbitration, Bangkok Postreported.
CAT will also complain to regulator NBTC accusing DTAC of using its 850MHz spectrum for unauthorized purposes.
But DTAC's initial free approach could allow it to keep the service in compliance with the letter of the license terms, CAT's president admitted to the Post.
DTAC has vowed to press on with its 3G plans regardless, insisting it has every right to offer 3G services under an earlier government permit.
The operator has long argued it needs to introduce 3G to prevent losing ground to its competitors' existing services.
Thailand's new ICT minister has pledged to act as a middle-man in the dispute between the companies.