[Asterisk-Users] Double NAT issues with SIP and workaround (?)

[Julian J. M.]

Hello,

I've been fighting one-way-audio issues with asterisk and SIP
extensions for some time..., and  I want to share with you my findings
;)

My setup:
    * 1 ADSL router (Zyxel)
    * 1 Asterisk box with private IP, and interesting ports forwarded to it.
    * Several extensions, some local some remote

The problem:
    * External extensions behind double nat don't get audio when they
initiate a call. But if the extension receives the call, there is no
problem.

The fix:
    * Get a Linksys WRT54G, and setup the adsl router in bridge mode,
giving the public IP address to the WRT.
   * Setup port forwarding and QoS (optional)
   * Enjoy VoIP ;)


I don't know the exact reasons why this happens, but it works ;).

Julian.