[joe@asterisk]# cat /etc/asterisk/sip.conf
[general]
context=invalid
bindport=5060
bindaddr=0.0.0.0
srvlookup=yes
disallow=all
allow=ulaw
allow=alaw
allow=gsm
allow=ilbc
language=fr
externip = 82.224.x.y
localnet=192.168.0.0/255.255.255.0
nat=yes
canreinvite=yes
qualify=yes

;Linksys office
[200]
type=friend
secret=test
nat=no
host=dynamic
context=myinternal
canreinvite=yes
qualify=yes

;GS remote
[204]
type=friend
secret=test
nat=yes
host=dynamic
context=myinternal
canreinvite=yes
qualify=yes

;Linksys VoIP gateway
[fxo]
type=friend
secret=fxo
nat=no
host=dynamic
context=myinternal
canreinvite=yes
qualify=yes