Users of the Symbian mobile phone operating system, meeting in London this week, hope that making the software freely available will help it regain momentum in the battle with new rivals like Apple and Google. The two-day conference is the first since Nokia, the world’s largest mobile phone maker, announced in June it would buy out its partners in UK-based Symbian for $410 million and make its software royalty-free to all phone makers. Nokia decided to set up the not-for-profit Symbian Foundation and make the 10-year old operating system open source and free from the first half of 2009.