Symbian has released version 9.3 of its operating system for smartphones, promising improved performance and shorter boot-up times for phones and applications.

Version 9.3 adds native support for USB 2.0 connections and the next-generation HSDPA wireless technology.

The software introduces native support for Wi-Fi radio and offers Unlicensed Mobile Access technology allowing the phone to switch between cellular and Wi-Fi networks using inexpensive VoIP technology.

The software also aims to please operators and manufacturers by making it easy to remove features on lower-priced models or add custom features to high-end models that allow for differentiation.

Symbian is one of the world's most popular operating systems for smartphones, shipping on 33.9 million handsets in 2005. The software competes with Palm OS and Windows Mobile 5.

Symbian is owned by a consortium of mobile phone makers. Nokia owns nearly half, and other shareholders include Samsung, Ericsson and Panasonic.