No SBC Needed for GoTrunk

When there are a plethora of SIP trunking providers available on the market, enterprises often find it difficult to choose between them. All of them seem to advertise similar inexpensive rates, service level agreements for uptime or downtime and claim to be easy to set up. However, not all vendors provide the same quality of service and each vendor may have their own unique feature that can prove to be the exact solution required by an organization.

No SBC Needed for GoTrunk

For instance, GoTrunk has a unique feature that is not commonly found among SIP trunking providers. Businesses that use GoTrunk do not have to install additional SBCs (Session Border Controllers) to help with accessing VoIP devices behind a NAT firewall. For those who are unfamiliar with VoIP terminology, it might sound like a bunch of gobbledygook. So let us take a closer look at what SBCs and NAT traversal means for VoIP systems.

NAT Firewalls and VoIP Devices

NAT or Network Address Translation is a technology that has been in use for decades. It provides a way for multiple devices situated on a LAN to share a single public facing IP address. These devices will have “private” IP addresses which means that they can be accessed only from within the LAN. A device that is situated outside the LAN i.e. on the public Internet will not be able to contact them as they do not have a public IP address.

This is where Network Address Translation comes in. These devices – commonly routers or firewalls – are situated at the point where the LAN meets the Internet. Any traffic coming from a device within the LAN will have the private IP address replaced by the public address of the NAT firewall. Responses sent back to the device will first go to the NAT router and it will redirect the traffic to the appropriate device based on its internal lookup tables.

As you can see, NAT quickly becomes a problem for VoIP calling. This is because when the traffic or connection is originated by a device on the Internet, the NAT device has no way of knowing where to send the traffic within the LAN. To complicate matters, VoIP utilizes different protocols for signaling/ call setup and sending the actual audio streams. So the NAT device has no way of knowing that the signaling and the audio traffic is connected and meant for the same SIP endpoint.

NAT Traversal and SBCs

Session Border Controllers are one way of overcoming the problems posed by NAT for VoIP calling. These SBCs are often located at the junction of different networks. So they may be installed at the point where different peering networks connect with each other or at the border between the enterprise network and that of the service provider (hence the name).SBCs are often required for enforcing security, quality of service and controlling the admission requirements for multiple VoIP sessions.

In addition to the above purposes, SBCs can also be used to help with NAT traversal i.e. allow VoIP sessions to successfully navigate and reach devices that are otherwise hidden behind NAT devices or firewalls. Enterprise users who are unfamiliar with the underlying technology often assume that simply deploying an SBC will solve any problem being faced by VoIP services. However, the SBCs will have to be configured and setup properly in order to effectively monitor VoIP traffic.

GoTrunk – The Advantages of Eliminating SBCs

On the surface both the problem and the solution may appear pretty straightforward. VoIP devices have difficulty in navigating NAT firewalls, so all you have to do is deploy SBCs and the problem goes away. However the reality is rarely that simple or easy. Depending on the complexity of the enterprise network, multiple SBCs may be required at different sites and locations. Purchasing and installing the SBCs can become expensive and complicated.

Since the GoTrunk service has the built in ability to reach IP PBX systems that are hidden behind NAT firewalls or routers, organizations do not have to invest considerable resources in purchasing, installing and maintaining session border controllers on their network. It is important to remember that each additional device that is installed on any network adds to the total complexity involved in managing the system.

Since NAT has commonly been used for decades within enterprise networks, the problem of VoIP sessions and NAT traversal is not going to go away. Organizations cannot afford to ignore PBX systems that are hidden behind NAT firewalls. Rather than relying on SBCs, utilizing services like GoTrunk often turns out to be the more cost-effective option for enterprises. Organizations are increasingly trying to get rid of Network Address Translation altogether on their networks but until then, the SIP trunking service from GoTrunk is a much better option for businesses of all sizes.