I'm connected to the swedish VOIP privider Cellip AB. I use their services with both standalone IP phones and software phones like X-lte and there are no problems. I use a Linksys RT31P2 router/firewall. When I connect the 3CX PBX to my provider it get registred and I can see the name of the PBX and ip address. When I try to call one of the two installed numbers the 3CX doesen't answer. I can make outbound calls even if it take some time for the call to establish. When I contacted my VOIP provider they told me to set the function "send internal ip always". I can't find such parameter. How do I proceed?