Re-implemented DND override for using ringer=urgent (Request: Andreas Anderon)

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4289 43c1dc8c-776e-4df2-8ef1-6e829299be21
Re-implemented DND override for using ringer=urgent (Request: Andreas Anderon)

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4290 43c1dc8c-776e-4df2-8ef1-6e829299be21