NAT Traversal

SIP Endpoint SDK supports NAT traversal for restrictive firewalls and routers in the following general scenarios:

• Enterprise to Cloud
• Consumer to Cloud
• Home Agent to Cloud
• Mobile to Enterprise
• Mobile to Cloud

To configure NAT, see the nat section of the Default Configuration Settings.

Important

• Double NAT is not supported.
• NAT translation will not occur with a NAT server that does not support UDP fragmentation. An example of such a server is Microsoft RRAS (Routing and Remote Access Service).
• NAT functionality was tested with the following NAT and STUN/TURN servers:
  • NAT Server—Windows 2008 NAT Server using RRAS service
  • STUN/TURN Server—https://code.google.com/p/rfc5766-turn-server/

• When using UDP transport for an endpoint behind the NAT, you must set the reg_timeout option to a value not exceeding twice the binding timeout for your particular NAT implementation.

  Periodic REGISTER messages serve as a keep-alive mechanism necessary to keep the NAT channel open. Genesys recommends a value of 60 for reg_timeout (REGISTER sent every 30 seconds) which should work with most NAT implementations.

Re-registration

Use the reg_match_received_rport setting in the proxyN section to control re-registration in cases where the received/rport values in the REGISTER response do not match local values. A value of 0 (default) disables this feature and a value of 1 enables re-registration.

<domain name="proxies">
    <section name="proxyN">
      <setting name="reg_match_received_rport" value="0 or 1"/>
. . .
    </section>
. . .
</domain>

Important

For re-registration to work correctly, the registrar must support RFC 3581. Genesys SIP Server does not support RFC 3581. In cases where re-registration may interfere with NAT traversal, the reg_match_received_rport setting can be used to turn off re-registration.