If your Vonage adapter is located behind a router that has firewall capabilities, and you do not want to reconfigure your network, you may need to set up Port Forwarding for your Vonage service to operate properly.
Port Forwarding can solve issues related to:
When you set up Port Forwarding, you are telling your router whenever data is received on a specified "port", send that data to a specific IP address.
The "port" being forwarded is not a physical port that you plug something into. Ports are used to identify data that is being sent over the Internet so that it will be received by the correct program. For example, when you connect to a website, the information that is sent to your computer is sent on port 80. Data received on port 80 is processed by your web browser. There are more than 65,000 ports that computers use to send and receive data. Vonage uses only a few of these ports for phone calls.
All devices on a network have IP addresses. By default, most devices are automatically assigned an IP address by the router the device is connected to. Since the router will not necessarily give the devices the same IP address every time, you will need to assign a static IP address to the Vonage adapter before setting up Port Forwarding. This will ensure the IP address of the adapter will not change. Instructions to assign a static IP address to your adapter are included in your adapters User Guide.
After you have assigned your Vonage adapter a static IP address, configure Port Forwarding on your router. Refer to your router's manual or the manufacturer’s website to learn how to configure Port Forwarding on your router.
The following ports are used by Vonage and may need to be forwarded to your Vonage Adapter.
SIP: Port 5061 UDP (Used to send and receive SIP information)
RTP: Ports 10000-20000 UDP. (Used to send and receive RTP traffic) When a call is made, random ports between 10000 and 20000 are used to carry the conversation. If any of these ports are blocked, you may experience one way or no audio.