At the ministry's daily briefing earlier this week, Thang said that the circular would also set floor prices for mobile phone services to prevent unfair competitive practices in the form of unlawful sales promotions.

Pham Hong Hai, director of the telecommunications department, said the lack of specific rules on mobile rates, including benchmark rates, made it difficult to manage the telecommunications market.

Some smaller mobile service providers, e.g., Beeline, had continued offering sales promotions believed to be illegal, said Hai. Beeline, operated by Russian telecommunications giant VimpelCom, last year launched a promotion campaign called the "billionaire" calling plan. By paying a small sum monthly, subscribers using "billionaire sim cards" would receive up to VND1 billion (US$47,620) on their accounts, giving them the ability to make calls for up to 10 years without limitations.

The ministry's deputy chief inspector, Le Huu Phuong, said the "billionaire" calling package offered network connections at less than VND10 per minute, while major providers were charging a prevailing rate of VND500-600 per minute

Beeline has countered that if it didn't offer aggressive promotions, it would face challenges in developing a customer network and expanding market share in an increasingly saturated market.

Hai predicted that smaller operators would continue to offer these sorts of promotions, and efforts by more established operators to compete with them would destabilise the market. He said that he had asked the ministry inspection team to strictly handle further violations.