O2 wants to end the "duopoly" of Android and iOS - and it's prepared to back Windows Phone to do it.
O2's parent company Telefonica has announced it will attempt to increase the visibility of Microsoft's Windows Phone 8 software in its stores.
The "enhanced marketing effort" will be launched for 12 months in the UK, as well as Germany, Spain, Mexico, Brazil and Chile.
Telefonica said that it wants to "encourage the presence of additional mobile operating platforms as an alternative to the current duopoly of Android and iOS".
It also wants to "provide customers with a more personal smartphone experience like Windows Phone offers".
"As part of the commitment, Telefónica will encourage growth in market demand for Windows Phone 8 while working with suppliers to ensure the availability of high-quality devices. It will be working with the leading manufacturers of Windows Phone 8 devices to make their commercial offering available throughout the duration of this enhanced marketing effort with Microsoft."
Windows Phone is currently in third place in the UK, and does have some momentum having recently doubled its marketshare to 8.4% in 12 months, according to Kantar Worldpanel.
Meanwhile the former third place BlackBerry OS has dropped to 5.6% from 13.5%, even after the release of BB10.
Microsoft and O2 will no doubt be looking forward to whatever Nokia announces on 11 July - thought to be its next 41-megapixel Lumia PureView.
But with iOS currently at around 28.7% and Android at 56.9%, it's going to be a while before Windows Phone troubles the leaders - marketing push or not.