The handset joint venture, which is headquartered in London, had to buy out companies that included Nokia Corp to secure Symbian, even though its Finnish rival has its own UI technology in the shape of the Series 60, 80, and 90 software that ships on its phones.

Now it is inviting any handset manufacturer interested in having an alternative UI to S60 and the other Nokia offerings to deploy on Symbian phones to become shareholders in UIQ, which is currently a 100% subsidiary of Sony Ericsson.

Per Aspemar, Sony Ericsson’s head of strategy, said that while the invitation is open, for us, the larger they are the better, and we’d probably like several. [When Sony Ericsson decided to acquire UIQ], we looked at the options out there and saw that there were no others for us from the point of view of differentiation, as well as the control and governance of the platform. It was a way of getting a Symbian UI that Sony Ericsson could use to differentiate its offerings from Windows Mobile and Linux phones, but also from Nokia’s Symbian handsets.

Having closed the acquisition on February 2, he said the vendor is now in a position to offer other Symbian players, or potential Symbian players, to buy back in. Co-ownership means comfort, in that the shareholder gets influence on the board, access to the figures and generally can guarantee corporate governance, he said.

Motorola is the other big UIQ licensee besides Sony Ericsson, which licenses the technology from its own subsidiary in order to keep it at arm’s length. While Greg Besio, its VP of mobile device software, described Symbian’s strategic role at Motorola as a niche play in an interview with Computer Business Review last year, Aspemar said: we hope they’ll reconsider [that position] and will try to convince them to become shareholders.

Motorola was present at the UIQ press conference at 3GSM yesterday at which Sony Ericsson announced the open invitation. It was there to plug its new Symbian phone, the Moto Rizr Z8, but this at least indicates that Symbian development with a UIQ front end is not dead at Motorola.

Aspemar said other targets for shareholdings are Samsung and LG, whose Symbian offerings to date have used Nokia UIs.

Apart from bolstering its standing in the industry by bringing more shareholders on board, Sony Ericsson also recognizes that it has work to do on the technology if it is going to compete on equal footing with the Nokia offerings, let alone with WM6 and Linux.

This was clear late last year when Vodafone Group Plc announced its three strategic platforms for handset development, and specifically stated that Symbian S60 was one of them alongside the Microsoft and Linux offerings. I don’t think UIQ was good enough for them to endorse it, said Aspemar. Now it’s up to us to convince them to change that, and if we can meet their criteria in terms of features, number of phones forthcoming and number of vendors working with the platform, I have to believe that they’re not going to be religious about this.

He said two areas are multimedia and what he called the phone application, communication with the radio chipsets and integration into contacts. In both cases, he said, we and Motorola had to source the technology externally. This is something that Sony Ericsson and UIQ want to change quickly. There’s been too much work on the licensee side to date, he said.

Other UIQ potential shareholders are Sharp, Fujitsu, and Mitsubishi. These are Sony Ericsson’s fellow Symbian phone suppliers to Japan’s NTT DoCoMo, which made the OS one of its strategic handset platforms a couple of years ago.