ServerA Sip.conf

[404]
type=peer
nat=yes
username=404
secret=password
context=hrsg-sip
host=192.168.128.120
disallow=all
allow=all


ServerB sip.conf

[404]
deny=0.0.0.0/0.0.0.0
secret=password1234
dtmfmode=rfc2833
canreinvite=no
context=from-internal
host=192.168.128.120
type=friend
nat=yes
port=5060
qualify=yes
callgroup=
pickupgroup=
dial=SIP/404
accountcode=
mailbox=404@device
permit=0.0.0.0/0.0.0.0
callerid=device <404>
call-limit=50
faxdetect=no


ServerA extensions.conf

exten => 404,1,Dial(SIP/404/404,30)