Worldwide sales of mobile phones to end users reached 419.1 million units in the first quarter of 2012, a 2 per cent decline from the first quarter of 2011, according to Gartner. This is the first time since the second quarter of 2009 that the market exhibited a decline.

T-Mobile USA has confirmed plans to cut a further 900 jobs, on top of the nearly 2,000 jobs lost earlier this year at its call centres.

The company currently has around 36,000 employees.

The company said in a memo sent to staff that the job cuts were due to "restructuring of key functions and departments across the company, including the elimination of some positions and outsourcing of others."

Earlier this year the company cut 1,900 jobs in its call centres after it consolidated them from 24 to 17 locations.