NAT traversal with session border controllers: Difference between revisions

Revision as of 00:41, 31 October 2019

Revision as of 10:45, 2 July 2023

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[[Network address translation|networkNetwork address translators]] (NAT) are used to overcome the lack of [[IPv4]] address availability by hiding an enterprise or even an operator's network behind one or few [[IP address]]es. The devices behind the [[Network address translation|NAT]] use [[private IP address]]es that are not routable in the public Internet.

The [[Session Initiation Protocol]] (SIP) has established itself as the de facto standard for [[voice over IP]] (VoIP) communication.<ref>Sinnreich, Henry; Johnston, Alan B. (2001), Internet Communication Using SIP, Wiley, p. 180, {{ISBN|0-471-77657-2}}</ref> In order to establish a call, a caller sends a [[Session Initiation Protocol|SIP]] message, which contains its own IP address. The callee is supposed to reply back with a SIP message destined to the IP addresses included in the received SIP message. This will obviously not work if the caller is behind a NAT and is using a private IP address.