For example, mobile phone numbers that start with "01" should be switched to an "081" prefix. The number (01) 234 5678 becomes (081) 234 5678.

Callers from abroad will have to add "8" after Thailand's "66" country code. For example, +668-1234 5678 would replace +66-1234 5678.

However, callers have until November 30 to get used to the new cellular dialling scheme. From December 1, only the 10-digit mobile-phone numbers will be valid.

All mobile-phone operators are now offering a free service at shops nationwide to convert numbers stored in handsets to the 10-digit format, regardless of the customer's service operator.

They will also send teams to busy shopping areas, such at Victory Monument and Silom as well as the offices of their customers to offer the conversion service.

Users also have to reconfigure the code of the short message function in their devices, which they can do by themselves or at operators' shops, to enable them to send and receive short messages. But they have a grace period until March 30.

Sigve Brekke, CEO of Total Access Communication (DTAC), said he would join more than 300 of his employees in spending the day in the Silom, Sathorn and Victory Monument areas to help people update their numbers.

The numbering plan aims to increase the total of phone numbers to 300 million from the present 90 million, which is expected to be enough to serve surging demand for 30 years.

Cellular-service providers have spent a combined Bt400 million upgrading their systems to comply with the new numbering plan.

The National Telecommunications Commission spent Bt30 million to publicise its new policy.

Telecom Reporters

The Nation