This takes a bit of a stretch because there are no GSM operators in South Korea. That nation is totally dedicated to GSM’s rival digital cellular standard — CDMA, which is shorthand for Code Division Multiple Access. That fact has made the Korea peninsula a black hole for GSM roamers – until now.
To roam there, Smart subscribers must bring their SIM (Subscriber Identity Module) cards and then insert them into a CDMA roaming phone, which is available for rental in airports and major hotels for a dollar a day.
Developed by Korea Telecom Freetel (KTF), these handsets enable GSM roamers to cross the digital divide.
The phones run on the CDMA network of KTF, which is Korea’s second largest mobile carrier. But they also accept Smart GSM SIMs so that a roaming Smart subscriber retains his cellphone number.
"This is the first time that a Philippine operator has established a roaming relationship with a network outside the GSM world," said Anastacio Martirez, Smart head for personal communications and mobile services division.
"This breakthrough will eventually pave the way for more extensive roaming arrangements that will allow Smart subscribers to tap not only the extensive global GSM network but also utilize CDMA networks in such key countries as South Korea, Japan and the United States," he added.
GSM is the most popular digital cellular standard and is particularly prevalent in Europe and Asia.
Major North American operators are also switching to GSM and are now establishing nationwide networks in both the United States and Canada. The ability to allow mobile phone users to roam in such a wide geographic area has been one of GSM’s competitive strengths.
Relegated to the background in the 1990s, CDMA recently attracted renewed interest because of technical advances that nearly double its voice capacity and boosts its high-speed data capabilities using existing radio spectrum. This is true of the CDMA/1x networks that have been rolled out in South Korea where over 30 million people now use CDMA mobile phones.
Major operators in Japan and the United States have begun or will soon deploy 1x networks as well and thus, will significantly expand the reach of advanced CDMA networks.
Until recently, it was impossible to roam between GSM and CDMA networks. The two cellular species were incompatible.
This digital chasm has been bridged by KTF’s innovative inter-platform service. First, there is the specially designed GSM-CDMA handsets which have slots for GSM SIMs and function in a CDMA network.
Then, there is the International Roaming Gateway System (IRGS) of KTF. The IRGS acts as the GSM-CDMA signaling conversion gateway, enabling the reading and delivery of International Mobile Subscriber Identity (IMSI) information from GSM home networks to the CDMA networks.
A data clearinghouse, meanwhile, handles the billing data and the financial settlement between KTF and its roaming partner, Smart.
In the future, technical advances will further integrate CDMA and GSM networks. In the works, for example, are dual-mode handsets that will run on both digital networks.
KTF, the mobile subsidiary of Korea Telecom and South Korea’s second largest mobile service provider, is the first CDMA carrier in the world to enable inter-standard roaming service with the SIM-compatible CDMA handset.