The Telecom Specs in NZ suggests that SUB ADDRESS is always on, so doing
"desk to desk" between offices each with an asterisk box over the ISDN
should then be possible, without a whole load of DDI numbers required.

(closes issue #15604)
Reported by: alecdavis
Patches:
      asterisk_subaddr_trunk.diff11.txt uploaded by alecdavis (license 585)
      Some minor modificatons were made.
Tested by: alecdavis, rmudgett

Review: https://reviewboard.asterisk.org/r/405/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@225357 65c4cc65-6c06-0410-ace0-fbb531ad65f3