With network operators worldwide treading carefully between expansion and squeezing more business from their existing resources, computer telephony systems specialist NMS Communications appears to have struck a profitable balance in supplying technologies to both camps. The Massachusetts-based firm recently claimed an innovation that it expects to be adopted in existing second-generation cellular services and in new high-speed, Internet-ready, third-generation (3G) mobile-phone systems. SK Telecom, one of the first cellular network operators to start 3G services, claims about 3.5 million subscribers and has signed up for a new, personalised service based on technology from NMS. The ring-back service called 'Color Rings' allows users to choose what people will hear when they call their phone instead of the usual ringing tone. Subscribers pay a small monthly fee for a limited selection of rings, and additional fees to select from thousands of ring sounds and melodies such as popular songs, classical music, and pre-recorded messages like 'Happy birthday to you' on SK Telecom's network. Users can choose tones for individual contacts, such as one tone for their spouse to hear or another for their boss. They can even choose one tone for daytime and another for the evening. Subscribers can make their choices from either a Web interface on a personal computer, mobile handset via wireless application protocol service, or an interactive voice menu service and do not have to download any new tunes into their mobile phone. The tones are played by SK Telecom's server computer, which replaces the ringing tone generator in the network switch. This makes adding and changing tones fast and easy. 'Subscribers have enthusiastically responded to this service. By using NMS' scalable, carrier-ready platform, we can expand the service easily as subscriber demand continues,' says Jang Yong-ha, engineering division vice-president at SK Telecom. 'The NMS platform was easy to integrate with our existing network, making it possible for us to deploy the Color Rings service quickly.' The service is based on NMS' Alliance Generation 4000, Convergence Generation 6500 and TX-series hardware and software platforms. 'SK Telecom moved quickly to capitalise on one of the last frontiers for customising the mobile phone experience. This service has great potential for enhancing subscriber loyalty and improving revenue,' says Critz Chan, NMS Asia vice-president and general manager. SK Telecom and NMS are currently moving to sell a similar capability to other phone companies in other countries. In South Korea, KT Freetel and LG Telecom have also rolled out a similar service. That has resulted in more than five million subscribers in the country alone. The ringback tone service was conceived from a personal experience of the Hong Kong-based Mr Chan during a business trip to South Korea. He received a call from the SAR, where the caller immediately identified his location as 'out of town' due to a different ringtone heard, while the connection was going through. 'It has happened to us at one stage or another that we know someone is on 'roaming' mode instantly, because the ringback tone was different,' he says. In the mainland, NMS has also worked with network equipment provider Beijing Sunny Capital Communications to deploy a voice-over broadband system at Leshan Telecom, a China Telecom subsidiary. Sunny Capital's SCX-1000 voice-over broadband product is based on NMS platforms and technologies, including the Convergence Generation 6100C high-density digital trunk interface and Signaling System 7 interfaces to the public switched telephone network. NMS was also engaged to provide planning, design, and implementation expertise that significantly expedited the field trial in the mainland. 'We chose NMS for this important project because of its proven platforms technology and experience in carrier-grade deployments,' says Shen Er, general manager of Sunny Capital Communications. The field trial at Leshan Telecom is particularly significant for Sunny Capital Communications to cultivate interest in its products across the mainland. 'Interest in broadband Internet connections, especially those based on digital subscriber line [DSL] technology, is on an upswing throughout the nation as operators seek cost-efficient options to satisfy the voice and data needs of business and residential customers,' says Mr Shen. Another Sunny Capital Communications trial is with a carrier in Sichuan province, which wants to provide a voice-over DSL service. These innovative services supported by NMS technologies are expected to benefit small and medium-sized enterprises in China and South Korea looking to reduce network costs by combining broadband lines for both telephony and data services. According to a report by telecommunications market analyst firm RHK, China and other key Asia-Pacific countries lead the world in DSL subscriber growth and network build-out. The region at present accounts for about 44 per cent of the world's DSL subscribers. RHK expects the growth trend to continue as China, Japan, South Korea and other countries in Asia upgrade their telecommunications infrastructure. 'These recent installations represent the global appeal of NMS offerings, and highlights our ability to respond to shifts in market requirements in the Asia-Pacific region,' says Mr Chan. Other prominent NMS customers include AT&T, Cable and Wireless, China Telecom, France Telecom, and KDDI and NTT DoCoMo in Japan. With nearly 20 years' industry experience, NMS designs both systems and system 'building blocks' for innovative voice, video and data services on both wireless and fixed-line networks.