(Telecompaper) Mozilla announced new phones running its Firefox operating system as well as plans to bring more low-cost and varied devices to the market. At the Mobile World Congress in Barcelona, its partners unveiled the latest Firefox phones, including the ZTE Open C and Open II and the Alcatel OneTouch Fire C, Fire E, Fire S and Fire 7 tablet. In addition, Mozilla said it's working with Spreadtrum on a processor to support Firefox smartphones at just USD 25. Mozilla said operators such as Telenor, Telkomsel and Indosat, and partners such as Polytron, T2Mobile and Thundersoft are expressing interest in the low-cost platform. The Indonesian operators are the latest to join the Firefox open web initiative, and Mozilla announced agreements with existing partners Telefonica and Deutsche Telekom to bring Firefox phones to new markets this year. Mozilla said sales of Firefox phones have exceeded expectations and it's receiving strong interest from manufacturers looking to adopt the OS. Amid plans to launch more varied devices and user experiences in 2014, Mozilla introduced a new self-service partner portal to help manufacturers bring devices more quickly to market. The company also plans to add new features to the next version of the Firefox OS, such as LTE, NFC, user accounts and more customisation options. For developers, Mozilla announced a new reference phone, the Firefox OS Flame, to test new apps, and it also extended its tablet developers programme to encourage more apps for larger screens.