Visitors walk at the Mobile World Congress, the world's largest mobile phone trade show.

Police officers cordon off one the main entrances at the Mobile World Congress.

Demonstrators from the Telefonica phone company protest against what they claim are unjustified dismissals from the company, outside the Mobile World Congress, the world's largest mobile phone trade show.

Attendees use their devices during the inauguration of the Mobile World Congress.

Attendees are seen in one of the pavilion of the Mobile World Congress.

Visitors use their mobile phones during the inauguration of the Mobile World Congress.

Visitors are seen in one of the pavilion of the Mobile World Congress.

A man holds the new Nokia Lumia 720 at the Mobile World Congress. Nokia unveiled a cheaper model in its Lumia smart phone range, powered by Microsoft's Windows phone software, as it tries to regain dominance in emerging markets like China. Nokia CEO Stephen Elop also revealed the Lumia 720, a higher-priced smart phone for countries like China that lack advanced wireless data networks. He said China Mobile, the world's largest cellphone company, will sell both models.

Stephen Elop, chief executive officer of Nokia speaks during conference at the Mobile World Congress.

A man walks with his phone at the Mobile World Congress.

Visitors walk in one of the pavilions of the Mobile World Congress.

This undated product image provided by Huawei, shows the Chinese company's new flagship model that it calls "the fastest smartphone in the world." The company said Sunday, Feb. 24, 2013, the device supports faster download speeds than other phones, but today's wireless networks aren't equipped to supply those speeds. The new phone, the Ascend P2, will have a 4.7 inch screen.