BANGKOK - True Move, Thailand's third largest mobile phone operator, said on Wednesday it expected to launch third generation mobile services in Bangkok in April.

True Move, a unit of True Corp TRUE.BK, has joined with state-run CAT Telecom to offer a trial service on the CAT network using HSPA technology, company chief executive Supachai Chearavanont told reporters.

"We aim to develop 3G services on an existing network and CAT has allocated the 800 MHz frequency to us," he said.

HSPA (high speed packet access), a super-fast 3G technology, will allow the company to support new devices such as Apple's (AAPL.O: Quote, Profile, Research) iPhone.

Investing in 3G on existing networks is one option for operators while they wait for 3G licences on a new 2.1 GHz frequency to be issued by industry regulators later this year.

"We don't know exactly when the new 2.1 licence will be issued. We have to do it now so that customers will be able to use 3G," Supachai said.

True Move, which will offer the 3G iPhone from Friday, plans to import equipment to upgrade the CAT network at 600 base stations at a cost of about 1 billion baht ($29 million), Supachai said.

True Move is the first operator to sell the sleek 3G iPhone in Thailand and more than 10,000 phones have been reserved online, he said.

True Move's contract to provide mobile phone services on the CAT network will expire in 2013, but CAT has agreed to a five-year extension, Supachai said.