| 摘要 |
PURPOSE: An apparatus and method for switching a call between a VoIP call and a PSTN call are provided to allow a user to switch to a PSTN call for continuous call communication if speech quality of a VoIP call is not good. CONSTITUTION: An IP network interface unit(230) interfaces an RTP(Real-time Transport Protocol) packet and a VoIP signaling bi-directionally. A digital signal processor(220) extracts a compressed voice signal from the RTP packet, converts it into a PCM(Pulse Code Modulation) signal, compresses the PCM voice signal, carries it on an RTP packet, and then, outputs it to the IP network interface unit(230). A subscriber line interface unit(210) converts a voice signal into a PCM voice signal and provides it to the digital signal processor(220), and then, a PCM voice signal outputted by the digital signal processor(220) into an analog voice signal. A VoIP/PSTN switching module(200) is selectively connected to the subscriber line interface unit(210) and to the PSTN for call communication. A CPU(240) controls an overall operation of call communication through a VoIP call or a PSTN call. A subscriber input unit(250) inputs an operation command according to user's manipulation too the CPU(240). |
