Do something with the service indicator so that asterisk does not attempt to use a chan_mobile endpoint that does not have service.

(closes issue #16132)
Reported by: nikkk
Patches: 
      service-indicator2.diff uploaded by mnicholson (license 96)
Tested by: nikkk


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@232544 65c4cc65-6c06-0410-ace0-fbb531ad65f3