Abstract: Provided is a method, a system, an apparatus, and/or a non-transitory computer readable medium for providing a ringback tone and a ringtone using a Voice over Internet Protocol (VoIP) call service. A call method may provide sound sources directly edited by users as a ringtone or a ringback tone in a VoIP call service.

Abstract: Provided is a method, a system, an apparatus, and/or a non-transitory computer readable medium for providing a ringback tone and a ringtone using a Voice over Internet Protocol (VoIP) call service. A call method may provide sound sources directly edited by users as a ringtone or a ringback tone in a VoIP call service.

Abstract: A double-screen simultaneous viewing circuit for simultaneously displaying two pictures on the main screen of a extra-wide television is provided. The two pictures each have a 4-to-3 aspect ratio and are displayed on left and right subscreens of the main screen. The viewing circuit includes first and second analog-to-digital converters for respectively converting first and second video signals of the two pictures into digital signals. The first and second video signals are respectively converted according to first and second clock signals which have equal frequencies and which are respectively synchronized with synchronizing signals of the first and second video signals. The digital video signals are stored in first and second memories based on the first and second clock signals, and the digital video signals are read from the first and second memories based on a third clock signal.