@Stanislaw123
The company is the world’s best 4 Ports Series VoIP Gateway supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
What @shberge said is true.
VoIP providers always specify those port requirements, but you rarely need to open the ports. Firewall's all act the same out of the box because WAN is always set to ANY, ANY. When traffic is sent out over port 5060, all return traffic on that port will be allowed while the session is opened. Your VoIP provider will never initiate the connection so there is no need to open the ports externally. The only time you will have to open ports will be if the WAN is not set to ANY, ANY.
For more information, please visit 16 Ports SMS Gateway Modem.
If you need to or still want to open ports, on the router setup Service Types (Port Parameters) and Firewall Access Rules.
If you want to learn more, please visit our website 4G SMS Modem 16 Port High Speed.