Trolltech Wednesday said it has partnered with software development services company Teleca in a move that Trolltech said signifies a growing interest in Linux by handset makers.For about a year, Teleca, a company that develops software for handset makers, has been using Qtopia, Trolltech's application platform for Linux-based device vendors, Trolltech CEO\u00a0Haavard Nord said. The companies have now decided to together develop a joint reference board and offer customization services for the platform.The partnership makes sense because customers often ask Trolltech for software development help, according to Nord. "Some of our customers like in Asia are mostly hardware engineers," he said. They often look to outsource software engineering, a service that Trolltech doesn't offer but Teleca does, he said.The announcement points to a growing interest in using Linux on mobile phones, Nord said. In 2005, 2 million phones using Trolltech's technology were sold.Phone makers are increasingly turning to Linux because it helps simplify an increasingly complex development process, according to Nord. The software for 3G phones is growing very complex and that is compounded by the fact that operators are asking handset makers for more and more specific capabilities, he said.With the proprietary software used by some of the big handset developers, though, making simple changes can be very difficult. For example, with proprietary software, upgrading a phone to include a 3G chip usually requires major work that could take as long as a year, Nord said. "With Linux, which has a more modern software architecture, this is very simple," he said. Handset makers "can stay with their proprietary operating system but that's going to be a competitive disadvantage for them down the road because it doesn't let them move fast enough."The proprietary operating systems also don't allow users to modify the source code so handset makers have less freedom to create the user interface they want, according to Nord. "Linux gives users the ability to build exactly the type of device they want," he said.That flexibility and the fact that Linux is open software mean that end users can expect to see more innovative applications on Linux-based phones, he said.Motorola is one of the major handset makers using Qtopia. Motorola's Rokr E2, the second version of the music player phone expected to become available in the first half of this year, is a Linux phone, built using Qtopia, Nord said.The mobile phone operating system space is growing increasingly competitive as phone developers and operators try to push features that are typically only available on high-end phones running Symbian or Microsoft Windows Mobile down into mass market phones. Linux supporters say that Linux, which is already a popular operating system on phones in China, is the best option for doing that.Trolltech also announced on Wednesday that Qtopia will be the application development framework on the Integrated Multimedia Solution for Linux being developed for the Intel XScale processor.