I've uploaded a first release of dectmon, a DECT protocol decoder. It can decode MAC, DLC and NWK-layer messages and show their content in a human readable form.
See http://dect.osmocom.org/trac/dect/wiki/Siemens#Traces for examples.
Details, including links to the git repository, can be found at http://dect.osmocom.org/trac/dect/blog/kaber-2010/10/27/dectmon_released