Starting in the third quarter, High-end Nokia N-series phones, running the Symbian S60 operating system, will come with Skype calling and instant messaging out-of-the box via 3G and WiFi. the companies announced Tuesday at the Mobile World Congress in Barcelona.

Scott Durchslag, Skype's chief operating officer, described the deal in the main blog.

He said: "It's a meeting of two great innovators and two great brands - the world's largest and most distinctive mobile manufacturer, and the world's leading communications software company. Together, we're going to develop and deliver a great mobile Skype experience that meets the needs of our many users who are also Nokia customers. It will also bring Skype to new mobile users in both developed and emerging markets."

He said Skype will be deeply integrated into the device's address book, "and calling using Skype will be very simple - it will be part of the phone's operating system, rather than a separate application, making it quicker and easier to start a Skype call or send an instant message."

Beginning in the third quarter, Skype will come pre-installed on new Nokia N97 devices, and existing N97 owners will also be able to get Skype functionality through a firmware update.

Downloadable versions of Skype already are available for the Android platform and more than 100 Java-enabled mobiles from Nokia, Sony Ericsson, Samsung, Motorola and LG, as well as Windows Mobile devices. More than 11 million copies of Skype for Windows Mobile have been downloaded. Skype is adding SMS and File Transfer features as well.

Durschlag said: "Clearly, the mobile industry is at an inflection point. This year will see software and content owners, device manufacturers and mobile operators looking at more ways to work together. What has traditionally been a relationship separated by walls, will increasingly be about an open, collaborative relationship and the common need to work together. The faster this can happen, the better."