Operators and handset makers are moving toward standardizing on just a few mobile phone operating systems. They're likely to choose relatively open platforms with large developer groups, according to experts at the 3GSM World Congress in Barcelona on Wednesday - but that doesn't necessarily mean that end users will soon be able to freely download lots of new applications, they said.Network operators are pushing handset makers to look for new operating system options on their mass market phones because the operators want to be able to sell customized handsets. Making changes to mass market phones that typically run on very old operating systems is increasingly difficult, said Peder Ulander, vice president of marketing for MontaVista Software, the developer of a Linux-based operating system for mobile phones.In addition, operators want to try to standardize on just a few phone operating systems which would make it easier to offer consistent services across a wide range of devices. Vodafone currently supports handsets based on more than 15 different platforms, said Dirk Wierzbitzki, group director of terminals portfolio and services at Vodafone. Tweaking each application to work on each platform is expensive, and because the operator must work to the lowest common denominator, it's not offering the innovative services that it wants, he said. As a result, Vodafone is looking to standardize on two or three platforms, he said. The company announced on Monday that the Symbian OS will be one of them.It may be some time before operators like Vodafone start pushing for Linux-based handsets, however, despite growing momentum from the Linux community for mobile products. "All big operators are considering handsets made with Linux," said Wierzbitzki. "But there's not one solution under the head of Linux that constitutes a phone." He said that the Linux space is too fragmented still in the mobile market, without a single platform that provides all the components necessary to build a phone. "What's needed is an effort to shape how Linux in mobile should work," he said, noting that some such initiatives have already begun.Another option for low end phones, being showcased at 3GSM, comes from Intrinsyc Software International, which offers handset makers a platform for developing mass market phones based on the core of Windows CE. Intrinsyc and Linux-based developers like MontaVista tout the large developer community that can create innovative applications for phones based on their operating systems.However, operators are at least currently reluctant to enable users to freely add new applications to their phones. "As an operator, we like openness but we want a certain degree of, I wouldn't like to say control, but ability to innovate," said Wierzbitzki.Operators are worried about increasing their support costs if users can download anything they want and they're also concerned about opening up the potential for viruses, said Randy Kath, vice president of mobile software products for Intrinsyc. "But the operators will have to make that leap," he said. Operators will need to rely increasingly on third party developers as demand grows for new types of services, he said.