排在第五名的因素是网内免费呼叫。
建议G . 171(1988年)“专用网传输规划情况”主要讨论完全在一个专用网内的呼叫。
Recommendation G. 171 (1988) "Transmission plan aspects of privately operated networks" deals mainly with calls wholly within a private network.
建议G . 171(1988年)“专用网传输规划情况”主要讨论完全在一个专用网内的呼叫。
Recommendation G. 171 (1988) "Transmission plan aspects of privately operated networks" deals mainly with calls wholly within a private network.
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