How to Support NAT Traversal in a VoIP Service

Network Address Translation (NAT) traversal problems happen sometimes when connecting a Voice over Internet Protocol (VoIP) phone on a local network for your business, which can make it challenging to use the phone. Thankfully, there are a few possible workarounds you can implement for your network.

Learn why NAT problems happen in the first place and how you can resolve the situation to communicate freely again:

What Is NAT Traversal?

Typically used by firewalls and routers, NAT enables multiple devices that are inside a single Local Area Network (LAN) to share just one public IP address. Each device has a private IP address already, but communication with other electronic devices via the Internet requires a public address. Because of this, NAT routers provide translations, and with this feature, each device can easily interface with others online.

NAT traversal is the term used for the translation that happens between these public and private addresses as devices within the LAN connect with and "talk" over the Internet. Before NAT-aware routers and devices, this turns out badly for VoIP service as the audio doesn't go to the right place. Essentially, this means the call fails altogether.

Why does this happen? Because NAT uses its own table to keep track of where everything comes from outside of the LAN. Communications starting inside the network have a specific source, and NAT records that source so it has a reference later when it does its translation. Unfortunately, this has one big problem when it comes to VoIP because not every conversation starts within the LAN. Sometimes an outside device starts the exchange, which can be confusing to NAT, who receives a communication but isn't sure where on the local network to send it.

How Does NAT Traversal Relate to VoIP?

NAT traversal gets complicated when it encounters Session Initiation Protocol (SIP), one of the key protocols (or "languages") behind many VoIP services. SIP-powered phones are very popular with VoIP. In the past, this meant the vast majority of VoIP phones could encounter this problem whenever they were placed in a LAN network.

To get around it, there are a few possible workarounds if your business is encountering problems:

  • Skip NAT: Avoid NAT and instead have VoIP devices use public IP addresses, so there's nothing to translate and no confusion.
  • Use a STUN server: This is a server with an open, dedicated VoIP port that can receive phone traffic past the firewall to avoid the NAT altogether.
  • Use a NAT-friendly firewall: Some firewalls are purpose-built to recognize VoIP traffic and let it through
  • Set up a single phone: With a single phone set up and specifically cited in the NAT's programming, VoIP traffic can be directed to a single point to avoid confusion.
  • Choose a public VoIP service: This way, you're not hiding VoIP devices behind a LAN and firewall that could become confused about where traffic is supposed to go.

Basically, you can either have a network that isn't spooked by VoIP and NAT, or you can skip over NAT so you avoid the problem completely. Keep in mind, though, many workarounds have implications for your system's security and make it more challenging to keep your VoIP communications secure.

How to Seamlessly Support NAT Traversal in a VoIP Service?

Seamless support for NAT, then, requires finding the right solution for your network and your own needs. To support NAT traversal, you likely will be using a system that recognizes and successfully navigates NAT instead of skipping over it.

You may need to consider a few possible solutions and how they would impact your network before you choose and commit to one option.

Getting Started With VoIP Technology

NAT traversal problems sometimes occur when setting up VoIP phones on a local network, but using a workaround to skip over or acknowledge NAT may be necessary if you want to use your VoIP system successfully.

Businesses rely on their technology to empower them to be as productive as possible. With 8x8's world-class technology you get everything your business needs in one place. Call 1-866-879-8647 or fill out an online form to request a no-obligation quote from an 8x8 product specialist.

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