The final block preventing British passengers from using their mobile phones on aircraft is to be removed, after Vodafone and Orange agreed to open their networks to the system.

The operators had refused roaming permission to OnAir, which provides mobile services to carriers such as Ryanair, amid fears that customers would be caught out by high charges. However, it is understood that within weeks the two operators will join O2 and T-Mobile in allowing customers to use the OnAir system.

Onboard mobile services are still new and only a few aircraft in Europe have the technology, but numbers are likely to grow rapidly. Antennae in the aircraft allow mobiles to make calls via satellites.

OnAir is the largest operator, with more than 20 airlines using or planning to use the system. Calls cost £2.50 a minute, but the mobile operators feared that their customers would suffer “bill shock” — surprise and anger when confronted by bills much higher than they had expected.

OnAir will make charges clear in brochures onboard and some networks will send a text message to passengers to tell them that they can use the system and how much it will cost.

Ryanair is using OnAir on some of its aircraft and British Airways will introduce the system for its service from London City Airport to New York this summer.

Benoît Debains, chief executive of OnAir, said: “There was concern that people would be horrified by the bill, but we have agreed with the operators how to do it and hopefully all passengers will be able to use the system soon. Cost is no big deal because the average communication is two minutes.”

OnAir has been available on 15,000 flights worldwide and it has gained a clearer picture of how people use the service. The highest volume of traffic is text and BlackBerry messages, but voice calls rise depending on the destination.

According to Mr Debains: “The British do not talk much, but the Italians talk a lot. It must be a cultural thing.” The number of people using the system rises after one hour because passengers on short flights will wait until they land to call or send texts.

The main complaint about allowing people to use mobiles in flight is that they might disturb other passengers. Mr Debains said that he had received no complaints as most passengers used their phones sparingly.

However, a Bill has been introduced in the US Congress that would make it illegal for passengers to make voice calls on aircraft in the United States, even if the technology is approved. Passengers would be allowed to make calls using existing in-seat phones or via an internet connection but not with a mobile.

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