Mobile phone giant Nokia has said it made a loss in the third quarter as it continued to come under pressure from other phonemakers.It swung to a net loss of 151m euros (£173m) in the three months to September, from a 322m-euro profit in the same period.Net sales fell 13% to 9bn euros.Nokia has lost ground to competitors such as Apple's iPhone and phones using Google's Android operating system.Shares in the Finnish phonemaker have plunged 41% so far this year.Nokia boss Stephen Elop has said he is "very optimistic" about the the company's new range of smartphones, which will use Microsoft's operating system instead of Nokia's legacy Symbian software.Earlier this year, Nokia announced thousands of job cuts as part of a 1bn-euro cost-cutting programme.In April, it said it will cut 7,000 jobs - with 3,000 of the posts being transferred to consultancy group Accenture - as part of strategy to focus on smartphones.