Is there anyone know how to config SMC router and Fortigate 100A firewall to achieve external extension call in? because I have set 3cx phone system behind SMC router and Fortigate 100A firewall, call between internal extension is OK, but when external extension call internal extension, voice only one way. so I think problem is NAT issue or firewall issue. But no matter how I config the router and firewall problem can't be solved. I hear someone talk about SIP-aware router or SIP aware firewall. Is it possible because SMC router and Fortigate firewall aren't sip aware or can't properly support sip??