Hello All, I have 3 sites and i have install 3cx phone system on Site no.1 The config on Site no.1: One PC with 2 Ethernet Cards, one for LAN: 192.168.1.8 and the other for Public 202.57.x.x I have set 3cx for listening port on Public side, with firewall checker return 0 for result. For Site. No.2 and No.3 with the same config: LinkSys PAP2NA behind NAT (Mikrotik Router Board) with DSTnatted (Port forward to LinkSYS) Port 5060 UDP Port 5090 UDP/TCP Port 9000-90049 UDP Stun Server to stun.3cx.com I try to call a SIP phone number in Site No.2 from Site No.3, it's ringing and connected but we can't hear each other. Please Help, Thank you. Paul.