Nokia increased its forecast for worldwide mobile phones sales this year and announced a new tool for operators to encourage mobile phone use in emerging markets.Nokia now expects mobile device sales to grow 15% in 2006, to about 915 million units, up from its previous estimate of 10% growth, it announced Thursday. The company cited strong subscriber growth.Nokia also reiterated its view that 80% of the next 1 billion subscribers will come from emerging markets, including half a billion from China and Asia-Pacific. It expects there to be 3 billion subscribers worldwide in 2008.To help accommodate the growth in emerging markets, Nokia announced a tool that will let operators offer a lower level of service to customers who can afford to pay only a lower subscription rate.The Market Expansion Toolkit lets operators allocate a full-rate or half-rate voice channel to customers depending on their subscription type. Half-rate channels use half the bandwidth of full-rate channels, which means service quality could be lower.This will encourage low-paying subscribers to make calls outside of peak hours, according to Nokia, and also allow operators to add low-paying subscribers without affecting service for existing customers. Many networks support the multirate capabilities already, Nokia said, so the tool can be used with existing equipment.Nokia, of Espoo, Finland, announced the software in Chongqing, a city in the center of China. The number of mobile-phone subscriptions in China reached 404 million at the end of February, after adding 106 million new subscribers during the previous year, according to China's Ministry of Information Industry.Nokia also introduced three phones at the event priced for emerging markets. The 2610, for "business-minded consumers," includes e-mail support and Internet access from a WAP (Wireless Application Protocol) browser. It's priced at $90 before operator subsidies.The company also introduced the 2310 with a built-in FM radio and the 1112, which has a simplified user interface for first-time mobile phone user. All three phones will be available in the second quarter, Nokia said.