Vigor Router supports VIP ALG. For most of the models, to redirect VoIP traffic to a server on LAN, we only need to set up Open Port on the router to forward the VoIP traffic (traffic on UDP port 5060) to the SIP server on LAN, and the router will forward the RTP traffic as well.
By default, The SIP ALG only inspects the traffic on port 5060. If the internal SIP server listens to other ports, please change the listening port via CLI by input
sys sip_alg port [port number]. For example, if the SIP server is listening to 5080, enter
sys sip_alg port 5080.
For the models that support VoIP gateway, note that the router's VoIP service has a higher priority than the Open Port settings. If you don't need the VoIP function, just disable it at VoIP >> General Settings page.
If you want to redirect the traffic on port 5060 to an internal server and use the router's VoIP function at the same time, you'll need to change the SIP Port from 5060 to other in every SIP Account. Also, if the SIP server on the Internet only listens to port 5060, you can set up Proxy and specify port 5060 at the end of the server's domain.
The example above means that the router will send out the SIP traffic from its port 5070 to the server's port 5060. Note that this might not work if the SIP server does not accept SIP traffic with source port other than 5060.