National prefix inserted even when caller ID not available

National prefix inserted even when caller ID not available

When the caller ID is restricted, the expected behavior is for the caller id to be blank.  In chan_dahdi, the national prefix is placed onto the callers number even if its restricted (empty) causing the caller id to be the national prefix rather than blank.

(closes issue #13207)
Reported by: shawkris
Patches:
      national_prefix.diff uploaded by dvossel (license 671)

Review: http://reviewboard.digium.com/r/220/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@188646 65c4cc65-6c06-0410-ace0-fbb531ad65f3