All the SIP clients need registered with the SIP server behind Vigor router.
By default, the UDP port 5060 is used by the VoIP module of Vigor VoIP routers. Since then, the following configurations need to be issued on Vigor router. Let's take Vigor 2910V as an example.
1. Open the UDP port 5060 to 192.168.1.10 by using open port function.
2. Change the SIP port in VoIP >> SIP account index menu.
Please note, all six SIP account ports should be changed.
Now the remote SIP client can register with the SIP server behind Vigor VoIP routers.
Vigor router will send the register message to 5070 port of the server. In order word, the UDP port 5060 can't be used by Vigor router's VoIP module and SIP server simultaneously.
Now, you may have another question. How can I use the router's VoIP module when the UDP 5060 port has been already opened to the internal SIP server ? It is quite simple. Please check the following setting.
With this setting, Vigor router will send SIP message from the UDP port 5070 to the server’s UDP port 5060.
Please note, some of the SIP provider requires client to use 5060 as the source port. Vigor router may not work in this case