Working with J-Phone, the Japanese cellular carrier owned by Vodafone, a video call was placed from Seoul to Tokyo this week between Young-Chu Cho, president and chief executive officer of KTICOM, and John Thompson, chief technical officer at J-Phone.
Both parties were using KTICOM handsets produced by Korea's LG Electronics, with Cho acting as a J-Phone user roaming in Korea and Thompson acting as a KTICOM user roaming on J-Phone's trial network. Calls were made in each direction to verify the function and also between two J-Phone roaming handsets on the Korean network.
To make the successful calls, KTICOM and J-Phone had worked together for five months on ensuring their networks, supplied by LG Electronics and Ericsson, were able to support the roaming function.
Roaming between 3G networks is seen as a key to their early success by both companies and J-Phone has held off on the launch of its 3G service in Japan so it can ensure the latest roaming specifications are supported by its handsets and network.
"Roaming is one of the reasons we chose W-CDMA over CDMA2000," said Byungki Oh, deputy director of KTICOM's global business team.
CDMA2000 is an evolution of the second-generation CDMA system and offers backward compatibility, making roaming between networks easy to accomplish. But the system suffers on the international level because CDMA is less popular than GSM, and to date many carriers have announced plans to use W-CDMA for their 3G networks.
"Our belief is that for international roaming it is a critical superiority of W-CDMA since [the technology] stems from GSM," said Oh. "Also, we think W-CDMA offers very good roaming services like video phone roaming, data roaming and other multimedia functions."
The trial call was made just days before J-Phone is scheduled to begin a trial 3G service. The carrier's plan calls for trials to begin on Sunday (30 June), working towards a commercial launch in December.
KTICOM is working towards a network launch in the first half of 2003, said Oh. The company is in the final stages of vendor selection for its initial network and LG Electronics, which supplied the trial system, is the leading candidate at present, he said. Local vendor Samsung and Nortel are also in the running, with Ericsson in last place.
The importance of roaming, in this case domestic roaming, can be seen from user reaction to the 3G service of Japan's NTT DoCoMo. The company's Foma service is based on W-CDMA and is the only commercial 3G service operating anywhere in the world at present.
Since its launch last October, subscriptions have been well short of company expectations at around 100,000 users, in part because of a limited coverage area and the inability to use the same handsets on the 2G network when outside the 3G coverage area.
KTICOM's Oh said the carrier is already planning dual-mode handsets that will allow users to fall back to 2G in places where a 3G signal cannot be received.