Subscribers to the next-generation mobile network services, called Long-Term Evolution (LTE)-Advanced, are expected to rise sharply down the road with a series of LTE-A smartphones expected to hit the shelves soon, industry sources said Tuesday. For the first time in the world, SK Telecom, the country\'s top mobile operator, introduced the mobile network in the country this past June, offering speeds twice as fast as the existing LTE network. LG Uplus Corp., the country\'s smallest mobile operator, followed suit in July offering its own service. To coincide with the service\'s initial launch, Samsung Electronics Co., the world\'s largest smartphone maker, rolled out its first LTE-Advanced smartphone in June. Its smaller local rivals -- LG Electronics Inc. and Pantech Co. -- also released their latest smartphones running on the LTE-Advanced network this month. The LG G2, the first device rolled out by LG Electronics after it dropped its Optimus brand, uses a quad-core Snapdragon 800 CPU, the Android 4.2.2 Jelly Bean operating system, a 13-megapixel rear camera and a 2.1-megapixel front-facing camera, and also comes with 2 gigabytes of RAM. The LG G2 also has all its buttons located on the rear of the device, making this the first smartphone to be completely devoid of side buttons. The Vega LTE-A, released by Pantech, with a Full HD 5.6-inch display, is equipped with the quad-core Snapdragon 800 and runs on the Android 4.2.2 Jelly Bean operating system. The device has a touchpad on its back that will allow users to easily control it with one hand, and also features a fingerprint recognition system that allows the user to unlock and operate the device. SK Telecom and LG Uplus are hoping subscribers to their LTE-Advanced service will rise down the road as handset makers are vying to produce LTE-Advanced mobile handsets. SK Telecom, which has attracted some 300,000 subscribers to its LTE-Advanced service since late June, is planning to roll out seven more gadgets running on the advanced mobile network this year. LG Uplus is also racing to sell six additional LTE-Advanced smartphone models by the end of the year. More smartphone users are also expected to adopt the LTE-Advanced service as their two-year contracts to the existing LTE mobile network begin to expire in September. The initial LTE service was launched in South Korea in September 2011.