Odd trixbox -> PAP2T one-way audio (but only with two lines in use)

  • I've got an odd problem with one-way audio. I'm looking for help troubleshooting this issue, but also in implementing the rest of this this with traffic shaping, etc. I'm willing to hire someone for some advice/assistance if they are knowledgeable in both trixbox and pfsense.

    I've got four locations: SiteA, SiteB, SiteC, SiteD. Sites A,B & C have a pfsense firewall. Site D doesn't yet, but will soon. There are two IPSEC VPNs SiteA<->SiteB and SiteA<->SiteC. SiteA has a trixbox system, a Aastra phone, and laptop with softphone. SiteB, SiteC & SiteD each have a single linksys PAP2T with two lines.

    My problem is an odd one-way audio problem. It occurs at each remote location (vpn or not). The problem manifests itself like so. If there is an external call in progress on line1, an external inbound call to line2 will have one-way audio. It doesn't seem to matter if the call on line1 is inbound or outbound. An outbound call on line2 will be fine.

    Two other clues. If I have the call recorded on the trixbox system, the call recording sounds fine. If I hangup Line1 while there is one-way audio on Line2, the audio problem on Line2 will resolve itself.

    I'm stumped.  With the VPN in place and the IPSEC rules wide open, I don't understand whey there would be an issue between the PAP2T and the trixbox.  Any suggestions on what might cause this or pointers to help debug this would be much appreciated.

  • Hi mate,

    You may set Manual Outbound NAT rule generation (Advanced Outbound NAT (AON)) for your subnet and Static Port to YES.


  • Thanks for the reply.  I've tried it with and without the STATIC PORT setting and it didn't seem to have any effect.

  • Hmmm.  Ok, I tried putting the PAP2T on the same LAN as the trixbox server to see if I would have the same problem.  On the same LAN, I don't have any of the issues that I reported in the original post which is good.  So, this problem occurs when the PAP2T is remote in either case (a) where the PAP2T is behind NAT on another network connecting via port forwarding to connect or in case (b) where the PAP2T is on a remote network at the end of a VPN tunnel to another pfsense box.

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