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How is SIP affected by NAT traversal?

April 26, 2017affected NAT SIP Traversal

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How is SIP affected by NAT traversal?

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SIP messages, which are carried inside of data packets, also include IP address information. Traditional NAT does not open the packet to change the IP information inside the SIP message. Therefore, the VoIP provider will not be able to send the call to the appropriate location. SIP requires a device to open the packet and adjust the IP information as it passes through the firewall. Some firewall devices, known as Application Layer Gateways (ALGs), have the ability to make this change inside the SIP message. Though several ALGs are capable of SIP NAT traversal, Bandwidth.com supports the Ingate SIParator and Edgewater Networks’ EdgeMarc router. Other firewalls, including Sonicwall and Cisco ASA/PIX, have this capability, but Bandwidth.com can only provide technical support for the Edgwater and Ingate ALGs.