Cell phones and music players have been some of the most popular Christmas presents for several years, but 2006 may be the season that will see the merger of these products. Wireless carriers offer a wide range of gadgets that combine both phone and music functions, and they come in a variety of shapes and sizes with large music libraries. The dual-function handsets frequently come at relatively low cost, and even free, with a two-year wireless contract. The introduction of the new phones could mean competition for Apple Computer Inc. and its iPod digital music player. The iPod currently dominates the market, and the company is said to be developing a combination music player and phone to compete with the devices offered by wireless carriers. The potential for growth in the music-phone market makes this space hard to Apple to ignore, and while the firm has sold over 60 million iPods worldwide, there are more than two billion cell phone users. Analysts report that about one billion cell phones will be shipped in 2006. The growth rate of music-phones will be more rapid than iPods because consumers always need a phone, and it only takes a short time to explore their features, according to Suzanne Cross, head of product marketing for Sony Ericsson in North America. Around the world, the industry is already seeing strong sales for cell phones that double as digital music players.