Nokia's Elop and Microsoft's Ballmer on phone deal

Nokia and Microsoft have formed an alliance that will lead to the Windows phone operating system running on Nokia smartphones.

The deal means that Nokia's existing operating systems will be sidelined.

Speaking at the launch of the partnership, Nokia's chief executive Stephen Elop revealed that there would be "substantial" job losses as a result of the tie-up.

Earlier this week he sent a memo to staff warning that the company was in crisis.

Rory Cellan-Jones spoke to Mr Elop and Microsoft chief executive Steve Ballmer shortly after the tie-up was announced.

He began by asking Stephen Elop why he chose Microsoft for a partner.