SIP, Externip & Nat, &RTP

Hello all…

I’ve googled a lot, and searched this site & others, and so far, no joy !

I am trying to have

  • a * box behind a nat router
  • sip clients anywhere (same network as the *, or elsewhere)
  • a voip provider in the world (other network)

everything works fine with IAX clients and SIP provider, but I like challenges and want to have clients running under sip (more soft/hard phone choices)

in the sip.conf,

When I put in the [general] section:

and in the [VOIPPROVIDER]

==> the SIP client can register, but the VOIPPROVIDER is reported UNREACHABLE - but I can dial a local extension (hello world) and hear correctly

if i comment out the externip and localnet, then the VOIPPROVIDER can be reached… but no voice can be heard
(yes, rtp.conf & ports on the firewall are opened - cf previous test)

What I am missing here ???

Your help will be greatly appreciated


How many NICs do you have in the box?
If you have 1, then nat=yes has to be used because you’ll have a private address to your voip provider - and you’d have externip/localnet set in this case.

I’d recommend using SIP clients if they are on the internal network, and IAX clients if they are on another network. It just makes the whole thing a lot easier.

Just one NIC - I agree, IAX makes life easier, but I need to connect hardphones, not softphones, from various places. Hence SIP !