Outgoing Settings
Trunk Name: pstn_spa
------------------
canreinvite=no
context=from-pstn
host=192.168.50.253
insecure=very
nat=yes
port=5061
qualify=yes
type=peer

Incoming Settings
User Context: spa3000
----------------------
canreinvite=no
context=from-pstn
host=192.168.50.254
insecure=very
nat=yes
port=5061
type=user