Symmetric NAT Traversal

Tmedia supports symmetric NAT Traversal that addresses the need of either side of the VoIP endpoint having a private network address. This endpoint device is situated behind a NAT (Network Address Translation) device. e.g. Firewalls. For "passive NAT mode", TMG detects the received RTP packet's source IP address and port. In response, TMG uses this source IP address and port as the packet destination for RTP.

TelcoBridges and NAT Traversal

Tmedia supports NAT Traversal starting from Tmedia release 2.6.31. Please refer to TMG-CONTROL version 2.6

Important Reminders

• All devices in the path must support symmetric RTP/RTCP: RFC 4961
• Currently, TMedia does not support advertising itself behind a NAT

How to enable passive NAT Traversal

• This feature is to be enabled per SIP NAP
• Go to NAP -> Edit -> NAT traversal -> Check "Enable"
• Save and activate your configuration

External Sources

• RFC 4961 Symmetric RTP / RTP Control Protocol (RTCP)