Ryanair has officially launched its in-flight mobile phone service on board 20 of its primarily Dublin-based aircraft.

The first step in fitting Ryanair's entire fleet with mini mobile phone masts, the company has now revealed pricing for the services.

Passengers on Ryanair’s "OnAir" enabled aircraft can now make and receive voice calls at non-EU international roaming rates of around 2 to 3 euros per minute.

Converted to sterling this means the price for calls is between £1.77 and £2.65 a minute.

Text messages will cost a minimum of 50 euro cents and and sending an email via a BlackBerry or other smartphone will set flyers back between 1 and 2 euros.

Ryanair says these price tariffs are set by each mobile service provider and are subject to each customer's individual price plan.

Flyers will now see a "Phone Use Permitted" sign on the OnAir aircraft and when the sign lights up green, will be permitted to turn their mobile device on.

The service will initially be available to O2 and Vodafone customers, with more operators due to be added soon.