FreePBX behind double NAT

Hi guys,

Currently I just setup freepbx behind double NAT (2 Mikrotik routers).
I registered extention 103 from Internet to to access FreePBX server.
I can make call to all extension, but can’t hear any sound from both side.

Please help???

|| WAN1 (Public IP
Mikrotik Router1
|| LAN1 (
|| WAN2 (
Mikrotik Router2
|| LAN2 (
FreePBX Server (
IPphone1(Extenstion 100)(
IPphone2(Extenstion 101)(

  • In router1, I did NAT UDP port 5060-5082 and 1000-2000 to
  • In router2, I did NAT UDP port 5060-5082 and 1000-2000 to
  • Ext 100 and 101 can be communicated as normal

In sip_nat.conf


Thank you for your comment.
I’ll try to change freepbx under only NAT.

Behind double NAT?? No not possible without VPN.

Use VPN or IAX protocol.

Is there any possible way to make SIP work?
Any idea please?

You will never get SIP to work through two NAT transitions. You IAX instead. It survives NAT much better.