The Gigaset T640/T440 has integrated hardware for connection ISDN lines.

  • T640: 4 ISDN 2 lines (8 voice channels)
  • T440: 2 ISDN 2 lines (4 voice channels)

Supported is:

  • PTP lines
  • PTMP lines

Not supported is S0 bus.

If more ISDN lines are needed, this should be done using external media gateways.

PTP LED indication.

If the PTP ISDN line is not connected or synchronisation signal is not available, the LED on the PBX will be "Red". This means the line is not working.

If the LED on the PBX is "Green" then the PBX recognise that from a hardware point of view the ISDN PTP line is connected and working.


PTMP LED indication.

The LED will be green even if the line is not connected as the synchronisation of the PTMP line is not mandatory and will be disabled in IDLE mode.



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