Domestic airline passengers will be able to make phone calls and send e-mails from the sky from next year, a local carrier has said. Shenzhen Airlines said on Monday it has signed an agreement with Geneva-based On-Air to provide passengers with in-flight communications services on all its planes by the end of 2009. The service will be introduced on three aircraft ahead of the 2008 Olympics, on two routes----from Shenzhen to Beijing and Shenzhen to Shanghai, the airline said. Passengers will be able to use their own electronic devices to send e-mails and short messages, make calls and surf the Internet, it said. The service is expected to be of particular interest to business travelers. According to a survey at the end of last year, China had 4.55 million mobile-phone subscribers. Ninety-three percent of those polled said they wished they could send and receive e-mails and messages while on a plane. Despite the introduction of the new service, passengers will still be prevented from using their cell phones and laptops when the plane is taking off and landing, or flying at less than 3,000 m above sea level, the official said. The official said the new service would not lead to an increase in ticket prices, but users of Chinese mobile-phone services will be charged the international roaming rate for any calls made from the sky. Shenzhen Airlines is the first Chinese carrier to provide such in-flight communications services. Its president, Li Kun, said installing the facilities will cost 4.5 million yuan ($596,000) per aircraft. However, the project still needs to be approved by the Civil Aviation Administration of China, a source said.4. Passengers will still be prevented from using their cell phones in the following situations except（ ）.