Hi Karman,
The problem with the # is that it is often interpreted as an end of dial digit. This can cause all sorts of problems when dialing or receiving calls.
Check that the End of Dial setting is set to No in the PBX settings of the D2400.
I hope this helps, if you need any further assistance please feel free to contact me at mhitchcock@blue-lava.co.uk
Mat.