1. Field of the Invention
This invention relates to signal transmission methods, and more particularly, to a signal transmission method that transforms signals over a network line to be suitable for transmission over a coiled-wire cord.
2. Description of Related Art
Recently, network phones are becoming popular because more and more people use networks and the cost of using networks to communicate with others is relatively low. A variety of network phones have come to the market, including a network phone having a USB interface, a network phone that directly attaches a network line to its handset, and a network phone that connects a network line to a station used with a wireless handset.
Functionally, a network phone transmits a digital communication signal via an Ethernet cable, for example, and converts the digital communication signal into an audio analog signal, so as to provide phone-like features. Network phones that use USB interface need to be used with a computer. Accordingly, such network phones are tethered or limited to the location of the computer. Moreover, for a network phone that attaches a network line to its handset, a user, when making a phone call, is restricted by the length and inflexibility of the network line, since the network line has a large line radius and poor elasticity. Further, such a handset often has a less than ideal appearance in terms of aesthetics, since it is directly connected to a network line. For a network phone that connects the network line to a station, since the station comprises a variety of components, such as a keyboard and a processor, a user typically has to manipulate the station to dial or access other settings, which is inconvenient and limits the use of space.
TW Pat. No. 574,812 discloses a dual-purpose (analog and IP) intelligent handset, which is applicable to a handset having both analog (POTS) and VOIP capabilities. The handset has a standard RJ-11 jack connectible to a conventional phone line, and an RJ-45 Ethernet port connectable to a broadband network such as ADSL. A user uses the intelligent handset, according to his needs, to make a variety of phone calls, such as a conventional phone call, a VOIP phone call, and an automatically switched phone call, so as to reduce telephone service fees incurred when using a conventional phone line, particularly for long distance. When the intelligent handset uses its “automatic switching function,” the handset makes a phone call, allows voice communication with other parties, and provides fast and convenient phone-paging functions. However, the user has to dial or access settings via a station, which is inconvenient.
Although the above connection methods work, users have grown accustomed to the appearance and usage of a conventional coiled-wire cord that is extendable and automatically retracts when not under tension to save space and conveniently organize the cord in a safe manner. It would be attractive to be able to provide a handset with IP capability that could use the familiar advantages of the traditional coiled-wire type of phone cord. Therefore, devising a method to transmit network signals via a coiled-wire cord, such that the method can be realized in a network phone to allow a user to dial and access settings with a handset, is highly desirable in the art.