While this is in theory possible with traditional telephone networks, access to switching equipment is easier to control.

虽然这对传统电话网络在理论上也有可能，但交换设备更容易保护。

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Instructing the switching network to realize the telephone communication needs much of equipment charges, lines charges, protection charges, project charges and time.

建立程控交换电话网络实现电话通信需要大量的设备费、线路费、维护费和工程费等费用，并且需要一定的施工工期。

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Instructing the switching network to realize the telephone communication needs much of equipment charges, lines charges, protection charges, project charges and time.

建立程控交换电话网络实现电话通信需要大量的设备费、线路费、维护费和工程费等费用，并且需要一定的施工工期。

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