| 摘要 |
A media gateway for coupling to both an Internet service provider frame switched network and a PSTN provider circuit switched network comprises an FXS port to which a telephony device may be coupled to initiate a connection to a destination. A programmable DSP includes a time-division multiplexing bus coupled to the FXS port and a PSTN port which couples to a subscriber loop of the circuit switched network. Compression instruction code is programmed into the digital signal processor in response to determining that the connection to the destination is to be established using a real time communication channel over the frame switched network. Time slot switching instruction code is programmed into the digital signal processor in response to determining that the connection to the destination is to be established over the circuit switched network. The time slot switching instruction code provides for: i) buffering digital audio data received from the FXS port during an occurrence of a periodic time slot assigned to the FXS port and transferring such digital audio data to the PSTN port during an occurrence of a periodic time slot assigned to the PSTN port; and ii) buffering digital audio data received from the PSTN port during an occurrence of the periodic time slot assigned to the PSTN port and transferring such digital audio data to the FXS port during an occurrence of the periodic time slot assigned to the FXS port.
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