吳榮根吳宗翰2019-09-052010-8-172019-09-052010http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22GN0696470588%22.&%22.id.&http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/106751Asterisk是一套實作了IP-PBX功能的開放原始碼軟體，允許使用者在一般 PC 上建置並實現一般電話交換機系統所該有的功能。不需額外的硬體支援便可以提供VOIP的服務。若要提供PSTN服務則必須透過FXS跟FXO介面的類比語音卡這類硬體的輔助。 本系統以Asterisk為基礎，配合自行製作的FXS和FXO介面類比語音卡及自行開發的驅動程式，在x86平台上製作一個成本相對低廉且具有彈性的網路電話交換機，可以同時支援PSTN服務及VOIP服務。 FXS和FXO介面卡均以PCI介面和系統連接。FXS介面卡上以SLIC連接電話機這類的終端設備，並利用DSP來處理語音資料的傳輸。此外，還有一個CPLD負責控制SLIC的SPI介面及提供PCM時脈。FXO介面卡的架構和FXS介面卡非常接近，只是SLIC被DAA所取代。 本系統中的FXS和FXO驅動程式負責啟動FXS和FXO介面卡上的IC，控制Zaptel和DSP間RTP封包的傳輸，並向Zaptel回報硬體的狀況。Asterisk is an open source software which implements functions of an IP-PBX. It permits users to build a PBX system on a normal PC, and implements the functions belonging to a PBX system. It can offer VOIP services without any hardware support. However, it needs hardware support such as FXS and FXO analog cards to connect to PSTN service. The PBX system described in this paper is based on Asterisk, and coordinates with self-developed FXS and FXO analog cards. We made a relative cheap and flexible PBX system on an x86 platform, and it interconnects VOIP service and PSTN service. The FXS and the FXO cards connect to the system by PCI interface. The FXS card uses SLICs to connect to terminations like traditional telephones. It uses a DSP to process the transmission of voice data. In addition, there is a CPLD on the card which controls the SPI interface of SLICs and provides the PCM clock. The Architecture of the FXO card is very similar to the FXS card, just replaces the SLICs with the DAAs. The drivers of the FXS and the FXO cards of this system take charge of enabling ICs on cards, controlling RTP packets transmission between Zaptel module and DSPs, and furthermore they report hardware status to Zaptel module.網路電話交換機PBXAsterisk