OnAir said Wednesday that it had signed up its first customer to provide in-flight mobile phone use in Europe. RyanAir, a budget airline, would retrofit its entire fleet of Boeing 737's with the company's mobile solution. The company expects service to begin in mid-2007 on 50 of its aircraft.

"This is a win-win for Ryanair, OnAir and most importantly our customers," the airline's CEO Michael O'Leary said in a statement. "The revenues generated by onboard mobile telephony will reduce our costs and help us to keep offering the lowest fares in Europe."

Users of the service would be able to both use SMS text messaging and place voice phone calls. Additionally, push e-mail services like those used in BlackBerry devices would also work, thanks to both a satellite network run by Inmarsat and a ground network operated by Monaco Telecom.

The system works via an antenna that that is mounted on the ceiling of the aircraft called a "pico cell." This antenna utilizes the GSM standard, which is supported by just about all phones in Europe. From there, the consumer's signal is transferred to the satellite, and then passed on to the ground network.

According to OnAir, the signal required to connect to this cell is so weak that it would not interfere with avionics, and customers would only be allowed to use the service at 10,000 feet or higher to prevent them from connecting to standard networks on the ground.

The cost of the service would likely not be as prohibitively expensive as airline phone services currently provided, although no pricing specifics had been given. However, executives for RyanAir said the cost would "mirror" that of current international roaming charges.

Three other airlines -- Air France, England's BMI and Portugal's TAP -- all plan to test out the OnAir system next year, but plans on an eventual launch by any of the carriers have not been disclosed.