DTIに関係するSIP.conf設定項目はこんな感じ。
[general]
language=ja
context=default
allowguest=no
allowoverlap=no
defaultmaxpiry=3600
maxexpiry=3600
defaultexpirey=3600
maxexpirey=3600
bindport=5060
bindaddr=0.0.0.0
srvlookup=yes
nat=route
register => にゃんにゃん@c-phone.dti.ne.jp:にゃんにゃん:にゃんにゃん@dti-1/にゃんにゃん
[dti-1]
type=friend
secret=にゃんにゃん
username=にゃんにゃん
fromuser=にゃんにゃん
fromdomain=c-phone.dti.ne.jp
host=voip01.c-phone.dti.ne.jp
context=outside
;insecure=very
insecure=invite,port
dtmfmode=inband
progressinband=no
canreinvite=no
disallow=all
allow=ulaw
qualify=yes
nat=route