Mine

Setting up extensions in extensions.conf (SIP)

Edit /etc/asterisk/extensions.conf with any editor

Add the following to [outgoing]
(this was not in the 'add box', this was the title of the section)
---------------------


exten => _1NXXNXXXXXX,1,Dial(SIP/${EXTEN}@exgn)
exten => _011.,1,Dial(SIP/${EXTEN}@exgn)

; for exgn caller id announce
exten => _811,1,Dial(SIP/811@exgn)

; e911 must be enabled. see DIDs > NPANXXNXXX > Action > e911
exten => _911,1,Dial(SIP/911@exgn)