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Nextiva Networking Guidelines

The ideal network involves your Internet Service Provider (ISP) connecting onsite to a stand-alone modem that connects to a router (preferably a router sent to you from Nextiva, preloaded with custom Tomato firmware for QoS). If you have more devices on your network than ports on your router, then you can connect a switch to your router to expand the number of ports. If you use an additional router instead of a switch, you will be creating a Double NAT.

So, what is a Double NAT?

A Double NAT is when a network device has to send messages through two routers to talk to the ISP. This makes it difficult for the messages to make it to and from their destination. There is no fix for a Double NAT other than replacing one of the routers with a switch.

Issues Involving Double NAT

Most issues involving Double NAT will be intermittent meaning it will work one minute then have issues the next. The reason is because the messages don’t always fail to get to and from their destination. Normally the more traffic a user has on their network the more likely they are to experience issues.

These issues can include but are not limited to:

  • One way audio on calls
  • Phone dropping registration periodically
  • Transfers not completing successfully
  • Error messages when dialing a number
  • Hunt groups not ringing or routing properly
  • Calls dropping involuntarily

How do you know if you have more than one device performing NAT?

In order to be able to determine if you have a Double NAT you need to know what equipment you have.

  • Modem – Talks directly to the ISP and gives out 1 single public IP address (Does not NAT)
  • Router – Gives out multiple IP addresses to the devices on a network (Performs NAT)
  • Gateway – This is a Modem/Router combination (Performs NAT)

NOTE: In most cases Gateways can be put in what known as “Bridge Mode” meaning they will only perform the Modem duties and leaves the routing to another device. (Does not NAT)

Routers are the only devices that preform NAT, and so you have to make sure you only have one router. In many instances, your ISP will sell or provide you with a gateway device that is a modem/router combo device. This device may work fine with Nextiva, but you cannot connect another router to it unless it can be bridged. If not bridged properly it will cause a double NAT.

Issues Involving Firewalls

Firewalls are primarily designed to keep unauthorized traffic from accessing your private network. In some cases the default firewall rules might cause Nextiva’s traffic to be blocked. The simplest way to avoid issues is to open up inbound and outbound traffic to/from our IP addresses.

How do you ensure your firewall is not blocking Nextiva’s traffic?

The simplest way to ensure that our traffic is not being blocked is to allow all traffic to and from and This range covers the IP addresses from –, and –

If you would like more information or have questions for our Amazing Team, please email us at, Submit a Ticket, or give us call at 800.285.7995.

Updated on December 27, 2016

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