A system for automatic call-transfer using a softphone, which applies the functions of a hardware telephone on a personal computer, is achieved by integrating a softphone system, a computer-telephony integration system, and a private branch exchange. This system is performed mainly in a manner of automatically fast swapping the first line and the second line of a call, when a call is transferred to an interactive voice system, for example, and this system can successfully compensate the fault that a holding noise emerges from the current telephone exchange device. When a call center operator talks with the customer, if the line needs to be transferred to a interactive voice response system but the interactive voice response system cannot pick up the line timely, this system can be used to transfer a call to avoid the customer listening the holding voice or rings of the private branch exchange.