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| セッション開始プロトコル トランキング (A mechanism for connecting the voice network of an enterprise to a service provider that offers public switched telephone network (PSTN) origination, termination, and emergency services without deploying PSTN gateways) | |||
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| セッション開始プロトコル トランキング (A mechanism for connecting the voice network of an enterprise to a service provider that offers public switched telephone network (PSTN) origination, termination, and emergency services without deploying PSTN gateways) | |||
