The Federal Communications Commission (FCC) has decided to keep in place the rule requiring passengers in the U.S. to turn off cellphones before takeoff. But the ruling might not be enough to end the debate thanks to new mobile telephone technology that is designed to circumvent traditional cellular ground networks.

Already common in Europe, so-called “smartphones” for the U.S. consumer market are on the way. Unlike traditional cellphones, smartphones use available Wi-Fi Internet connections to route calls without tapping into the ground cellular infrastructure. Passengers one day might be allowed to use such phones on aircraft equipped with onboard Wi-Fi connections without violating the FCC’s rules, according to industry insiders. If the technology can be proved safe, the FAA also is likely to allow the use of smartphones.

Lingering uncertainty about whether cellphone calls placed by airline passengers would cause interference with the cell system on the ground prompted the FCC last month to drop a longstanding proposal to relax the current ban. FCC chairman Kevin Martin said it’s unclear at this point whether cellphone calls placed from aircraft would contact multiple cell towers simultaneously, a phenomenon that could potentially disrupt the broader cellular system below, he said. As a result, the commission has decided to end its examination of the issue.

Technology has been developed to prevent such interference, but several of the nation’s largest cellular providers told the commission that a variety of technical and engineering issues have yet to be adequately resolved. As a result, the FCC, which has been studying the issue since 2004, said it will keep the cellphone ban in place for now. But the topic could come up again. The agency said it might “reconsider this issue in the future if appropriate technical data is available for our review.”

In the meantime, Air France and Emirates continue to push ahead with plans to become the first airlines to offer in-flight mobile phone service for passengers. Air France is using onboard equipment from OnAir, a partnership between Airbus and SITA, for its trial service. Dubai-based Emirates has contracted with AeroMobile, a joint venture launched by Arinc and Telenor, to provide similar access. Regulators in other parts of the world appear more amenable to the idea of allowing the use of personal mobile phones in flight. Equipment makers claim that they can control the devices, thereby ensuring that passengers’ phones are operating at extremely low power settings that won’t interfere with towers on the ground.

Concepts from OnAir and AeroMobile use onboard pico cells to intercept phone signals and route them through the airplane’s existing satcom system. Once Inmarsat introduces its SwiftBroadband high-speed aero data service later this year, passengers might also be permitted to use the Wi-Fi connections on their smartphones to make calls–if airlines decide to equip their cabins with Wi-Fi gear. In the U.S., AirCell is planning to roll out an air-to-ground broadband service for airline and business jet passengers early next year. Smartphones one day likely will be compatible with the system, according to an AirCell spokesman.

AirCell initially will deploy about 80 ground stations, providing coast-to-coast coverage for aircraft flying above 10,000 feet. Business jet operators who install AirCell Axxess hardware will be able to connect to the Internet using their personal laptop computers, make calls through the Iridium satcom service and, perhaps eventually, use their Wi-Fi-enabled personal communications devices to talk on the phone, retrieve e-mail, and send and receive text messages.