Josh Miller/CNET

Opera and Microsoft have signed a licensing agreement to put Opera's mobile browser into Microsoft's current feature and Asha handsets. These include the Series 30+ and Series 40 handsets that were formerly under the Nokia branding.

According to the terms of the agreement, current phones that are using the Xpress browser will be encouraged to upgrade to Opera Mini, while fresh devices from the factories will have Opera pre-installed.

One advantage Opera has with its Mini browser in emerging countries is the built-in data compression features, which help users with limited data caps get more out of their plans.

Currently, Opera Mini has 250 million users and around 100 million of them are using Android smartphones.

Opera's agreement with Microsoft does not appear to extend to Windows Phone devices, which currently has a mobile version of Internet Explorer as default.