Ho Chi Minh City telecommunication authorities have asked service providers to suspend more than 35,000 pre-paid subscriptions which were not registered with correct personal information.
Most of the subscriptions were customers of the three major providers - Viettel, Vinaphone and MobiFone.
The suspension order came after an inspection conducted in October by the HCMC Department of Information and Communication at seven cell phone service providers in the city.
A government order issued in 2009 requires pre-paid mobile subscribers to register their personal information including names, date of birth and ID or passport number to their providers by the end of the year.
The providers were required to continue requesting information from new subscribers.
But the order has not been followed, with promotion SIM cards sold widely on the market. One customer could own a dozen phone numbers without giving any personal information. The cards, also known as spam SIM, are usually sold for three to four times less than the money in the card.
The owner of a SIM card shop in District 10 said all the promotion SIM cards are registered under some fake names. "Customers just have to buy them and throw them away when the money runs out," she told the Tuoi Tre newspaper in a report December 17.
Le Manh Ha, vice chairman of the city government, said the providers will be fined for their violation.