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NAT traversal at the near-end or far-end represents a significant challenge for the SIP protocol as both signalling (SIP) and media (RTP) needs to be mapped to traverse NATs successfully. Up to and including sipXecs release 3.10 an external Session Border Controller (SBC) is required for NAT traversal. Typically we have used either an Ingate SIParator or an Intertex IX-67 SOHO SIP firewall/router. Other products might have but we have not done any extensive testing. In particular it is said that Patton Electronics SmartNodes might work.
As of release 4.0 sipXecs includes native support for both remote worker configurations as well as SIP trunking. There are two services utilized for this sipXrelay for NAT traversal and sipXbridge for trunking support. Use of these services is only encouraged for Lab purposes only. These services do not scale properly and do not support a HA configuration. The user should utilize a session border controller for this functionality.
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