Most of the 550 million cell phone users on China's mainland will feel disappointed that the new mobile roaming fee plan has been delayed until April 1.

Mobile carriers have complained that they are not able to start the new plan as scheduled because of technical problems.

The new plan, which slashes current fee charges by up to about 70 percent, sets a ceiling of 0.6 yuan (8 US cents) a minute for making calls while traveling in another province and 0.4 yuan per minute for receiving calls.

Only people who are not on contracts will be able to enjoy the new charges from Saturday, the original starting date.

Most phone users on contracts will have to wait for another month to enjoy the new prices, according to a joint announcement issued by the Ministry of Information Industry and the National Development and Reform Commission.

Major telecom operators said it was too difficult to adjust their systems within the time allocated.

"The network is different from mechanical equipment. It needs adjustments based on the signals delivered and received. It might look simple but in fact, it has to deal with a variety of situations," Yang Peifang, secretary general of Expert Commission of the Ministry of Information Industry, was quoted as saying by CCTV.

Shanghai Unicom, the local branch of the country's No. 2 mobile carrier, said it would try its best to finish the new charging system by the March 1 deadline.

"We will pay back any extra money charged next month if the technical problems cannot be solved in time," Shanghai Unicom's spokesperson Deng Yunlan said.

Shanghai Mobile said it would obey the MII's regulations but declined to make any other comment.