UCM6510 SIP Trunk not working on LAN port


Hello everyone, we have an issue with our UCM6510. SIP Trunk doesn’t work. The WAN port is connected to the internet for the use of GS Wave applications and the LAN port is used for SIP Trunk. We added a static route to connect to the SIP provider network but it still doesn’t work. Static route as follows:
Mode: Dual
Destination : @IP of the SIP Server(Provider)
Mask :
Gateway : @IP of the LAN interface
Interface we choose LAN2.

When we place a call using the SIP Trunk we can hear the person we are calling but he can’t hear us. Voice traffic is working one way only


Any reason why you don’t just use the WAN port for both?

Most common causes of one way voice is likely down to either RTP ports not getting through or, more likely, in the PBX Settings -> SIP Settings -> NAT make sure you list any “internal IP subnets” in the address list at the bottom:


Check those first as they are the common causes for us and our customer base and generally we only use the one WAN connection to the PBX as keeps it simple.


as asked above. Any reason for dual mode? I have never used it, only Route if I need phones on their own network or Switch. My preference is set the mode as switch and just use either the WAN or LAN port.