T interface

Abstract: A test device and a method of testing are provided for an integrated services digital network (ISDN) system having a Network Terminator (NT), a system/terminal (S/T) interface for coupling the NT to a Terminal Equipment (TE), a transmit line between the S/T interface and the NT to permit a TE coupled to the S/T interface to transmit D channel and B channel information to the NT, and a receive line coupled between the NT and S/T interface to permit a TE coupled to the S/T interface to receive D channel and B channel information from the NT. The test device performs an initial line connection test to determine if a satisfactory line connection exists between the NT and the S/T interface connected by the transmit and receive lines by providing a predetermined signal to the NT from the test device and for evaluating a response from the NT to the predetermined signal. A satisfactory line connection between the S/T interface and the NT is indicated if the response from the NT is a predetermined response, while an unsatisfactory line connection is indicated if the response is not said predetermined response. A plurality of additional tests are performed after the initial line connection test to determine the location of a problem in said line connection if the initial line connection test indicates that the line connection between the S/T interface and the NT is unsatisfactory.

Abstract: A CPE such as an ISDN telephone subset or multimedia equipment includes an interface recognition unit that connects to the network interface and adapts itself to allow the CPE to be used with standard ISDN interfaces and an analog interface. The interface recognition unit includes an interface recognition switch (IRS) that performs two functions. First, the IRS protects the CPE from damage in those instances where a non-standard network interface is connected to the CPE. Second, for standard interfaces, it identifies the type of network interface and routes the incoming signals appropriately. Specifically, if the IRS detects a T interface, the incoming signals are switched directly to a T interface circuit for controlling and powering the higher functions of the CPE. If the IRS detects a U interface, incoming signals are automatically switched to a U interface circuit for controlling and powering the CPE. Alternatively, an interface adapter is provided that delivers the signals to circuitry relating to one of the standard interfaces and monitors the CPE to determine if it is operable. If the CPE is operable, the connection is maintained. If it is not operable, the interface adapter reroutes the signals to circuitry relating to a second one of the standard interfaces. The CPE is again monitored to determine if it is operable. If it is operable, the connection is maintained. If it is not operable the connection is blocked. The IRS and interface adapter can also detect if the network interface is an analog line and route the analog signals to an analog circuit provided in the ISDN CPE such that the ISDN CPE can function as an analog telephone.

Abstract: 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 then serves 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.

Abstract: A system is disclosed which permits simultaneous multiple switched type communications on a basic access integrated services digital network (ISDN) without changing the standard frame format for transmission on the S/T interface. Simultaneous communication by up to 2N terminal equipments is achieved by defining a multiframe of N subframes, and separately allocating each of the 2N time slots of the B-channels within the N subframes to up to 2N terminal equipments for simultaneous communication over a single S interface bus.