I cannot find the trunk information under sip.conf, but there is trunk info from user. conf.
But the format seems different:
-GSPSTN
context=DID_GDPSTN
host=gd.homeip.net
username=GDPSTN
authuser=GDPSTN
fromuser=GDPSTN
fromdomain=gd.homeip.net
secret=xxxxxx
insecure=very
contact=
port=5061
qualify=2000
trunkname=GDPSTN
hasiax=no
registeriax=no
hassip=yes
registersip=no
trunkstyle=voip
hasexten=no
disallow=all
allow=all |