Here are the trunk settings:
vitel-inbound
type=friend
dtmfmode=auto
context=from-trunk
insecure=port,invite
canreinvite=no
host=inbound28.vitelity.net
vitel-outbound
type=friend
dtmfmode=auto
context=from-trunk
canreinvite=no
host=outbound.vitelity.net