Reference:Configuration/BRI/Physical

The basic settings of the ISDN interfaces (TEL, PPP, BRI, PRI) can be made here. The settings described here do not occur in every interface. The settings marked with a * are only visible with an existing ISDN PRI interface.

• NT Mode: The interface is operated in TE (Terminal Equipment) mode as standard. It behaves like a normal ISDN terminal and synchronises itself to the network clock (clock slave). A checked check box operates the interface in NT (Network Termination) mode. It behaves like an ISDN network termination (NTBA) and provides the clock pulse (clock master).
• Clock Mode *:

• Derived from NT mode (the device’s clock pulse is derived from NT mode).
• Slave (the device obtains its clock pulse from a different device, a clock master).
• Master (the device provides the clock pulse).

• Swap tx/rx: Switches the interface of the transmit line with that of the receive line.
• 100 Ohm Termination: Turns on 100 Ohm bus termination.
• Supply Inline Power: A checked check box turns on the power supply for the relevant interface.
• Do not use for synchronisation: The ISDN network usually generates a time stamp in the Connect message. This is used by telephones or PABXs, for example, to set their own clock at the first connection. The devices usually pass on such time stamps, unchanged. However, it may be desired to have the current system time of the device consistently used as the time stamp in all Connect messages. This can be achieved with the "Do not use for synchronisation" setting. Here, the list box must not be enabled. The device must then always have the correct time. Since it does not have its own real-time clock, an NTP server should be configured for this purpose. See also the chapter entitled "Configuration/General/NTP". This setting usually only makes sense in NT mode.
• µ-law: This check box must be checked if the device is located in a country that uses the ISDN µ-law standard. This includes the North America and Asian region, for example.
• Permanent Activation: Activates the line permanently. Only in TE mode.
• T1 *: Switches the interface from the E1 European standard (2MBit/s or 30 ISDN D channels) to the T1 American standard (1.544 MBit/s or 24 ISDN D channels), which is used in the US, Canada and Japan.
• CAS *: With the CAS method (Channel Associated Signalling), the signalling data (E1 = 16. D channel, T1 = 24.D channel) is transmitted on the same channel as the actual data. Here, one refers to in-band signalling.

 Caution
 If you enable the CAS method, the content of chapter 

"Configuration/PRI1-n/Protocol" changes.

• No CRC4 *: A checked check box disables the Cyclical Redundancy Check. No check value is then generated when transmitting data via the relevant interface.
• Relay Off *: Disables the relay function or closes the relay of the power-off loop.
• Loopback *: A checked check box enables the loopback function. This is only necessary for test purposes. The loopback function simulates a connected device on the relevant interface.
• Txlevel for T1 mode *: Allows the signal volume for T1 mode to be adjusted in decibel. The signal in T1 mode may be increased by 0db, 7.5db or 15db.
• Send flags on FDL *: A checked check box transmits FDL messages (Facility Data Link). Concerns T1 mode.