[Orgmode] how to get the time range difference with "C-c C-y" for inactive timestamps

[Rainer Stengele]

Carsten,

I wonder if it would be possible to also get the time range difference with 
"C-c C-y" for inactive
timestamps that do not show in agenda view like these:

[2007-09-20 Do 11:35]--[2007-09-20 Do 11:36]

Logging the length of a telephone call I use inactive timestamps rather than 
active ones.

Rainer