| 摘要 |
Network terminating terminal apparatus, for use in an Integrated Services Digital Network, comprises a U-interface and a S/T interface. The U-interface allows the integrated terminal apparatus to communicate with a central office directly, without a separate network terminator. Remote terminals may be connected to the network terminating terminal apparatus, via its S/T interface. The network terminating terminal apparatus serves then as a conventional network terminator. The network terminating terminal apparatus includes circuitry for controlling D-channel access by the integrated terminal apparatus. The circuitry detects the framing of the signal received at the U interface and the D-channel information from the remote terminals and ensures that the D-channel data from the integrated terminal apparatus is supplied to the S/T interface at the appropriate time for insertion into the D-echo channel of the signal returned to the remote terminals. In addition, the D-channel data from the integrated terminal apparatus is supplied to the U interface, with the D-channel from remote terminals, for transmission in D-channel of the signal to the central office.
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