Handle VIA received: yes
Handle VIA rport: yes
Insert VIA received: yes
Insert VIA rport: yes
Substitute VIA Addr: yes
Send Resp To Src Port: yes
STUN Enable: yes
STUN Test Enable: no
STUN Server: stun.sipgate.com:10000
on your line menu set
NAT Mapping Enable: yes
NAT Keep Alive Enable: yes