IP Talk Corp. said Monday it will start providing Internet-protocol mobile telephone services in March, allowing free calls between subscribers and extremely low rates for calls to fixed-line numbers and overseas.

The Tokyo-based telecom venture said it is expected to be the world's first IP mobile phone service. Handsets for such a service have been put on sale in the past but no actual service has been launched, according to IP Talk.

The company said that for the moment, its IP mobile service will be available only within the buildings of companies that have subscribed to the service.

While the available area for communication is limited, the service could prove popular because it will reduce companies' call costs.

The basic monthly fee for the service will be 3,980 yen. Subscribers will have to rent the handsets.

Domestic calls between subscribers and fixed-line telephones will be charged at 8 yen per three minutes, compared with 70 yen to 90 yen per three minutes currently charged by regular mobile phone firms.

Using the service to call overseas will be as cheap as 10 percent of the rate charged by mobile phone firms, IP Talk said.

An e-mail service and Web browsing will be available free of charge, it said.

The company said it will accept subscriptions through its Web site beginning next month.

IP Talk was established in April 2002. Its Web site is www.iptalk.net.