说明： PSTN to PSTN Dialing via SIP Network.This is a representation, as a slide show, of the SIP examples detailed in RFC 3666 - RFC3666 SIP PSTN Call Flow. (PSTN to PSTN Dialing via SIP Network.This i 's a representation, as a slide show. of the SIP examples detailed in RFC 3666- RFC366 6 SIP PSTN Call Flow.)
