Symmetric NAT Handling Disabled = break SIPBroker
 

I'm current using SIP Broker as my VOIP for dialing 1800 numbers. When I set Symmetric NAT Handling to YES, I can make these calls but when I set it to NO I have no Incoming audio. I've successfully made calls with other providers when turned OFF Symmetric NAT Handling and audio optimization ON. Any else experiencing this problem?

What kind of SIP user agent do you have?

Verify that your sip device/software is sending an SDP packet with your public IP address, not your LAN IP address. The problem may not occur with other providers who proxy all the voice traffic, or take measures to correct for having the LAN IP address in the SDP packet's "Connection Information" line.

Try using a STUN server.

If you prefer not to use a STUN server then do the following:
1. In your SIP client, set STUN Enable: no
2. In your router, forward the SIP ports and the RTP port range to your SIP ATA/phone.
3. In order for the ATA/phone to know it's public IP address, make sure the ATA/phone is registered with at least one SIP registrar, or enter the public IP address into the appropriate setting in the ATA (in Linksys ATAs this setting is EXT_IP).

I'm using the X-Lite softphone. I've set up both Port forwarding on my router (port 5060-5080 and 10000-20000) as well as using stun.voxalot.com STUN server. What can I use to detect if my public IP is set in the SDP packet?

There may be some logging option in X-Lite that would show SIP packets. Wireshark is packet monitoring program that works well. If you send me your Voxalot number I can call you and see what Wireshark shows.

I got the call. Any information from it? And I just want to add that I only have this problem with outgoing calls. Incoming calls seem to work fine.

I captured an SDP packet but still not sure what's going on. To which Voxalot proxy are you registering? Is your softphone using TCP transport? UDP transport is normally used for SIP and RTP packets.

I belive it's using the standard UDP. I'm going to try enable DMZ on my router and see what happens because port forwarding doesn't seem to be working.


Update:

Enabling DMZ works for me while port forwarding isn't working. I'm using a WRT54G router running DD-WRT. I was forwarding ports 5060-5080, 10000-20000, and 40000-50000. That alone isn't enough. Anyway, thanks for investigating the problem for me.

The "HowTo: 6 Steps To Tune Your Voice Quality" guide should be updated with a tutorial on how to setup proper port forwarding. Anyone has any success with port forwarding?

What ATA are you using... it helps to match the forwarded ports with the range of ports your device uses for the RTP stream...

I asked about tcp because I saw tcp mentioned on two different lines in the SDP packet sent by your SIP unit. One was in a Record-Route line (inserted by Voxalot). The other instance was at the end of a Contact line (written by your sip unit). Both lines are shown below (I changed your Voxalot number and IP address).

Record-Route: <sip:64.34.163.35;transport=tcp;lr;r2=on;ftag=dhbd b>
Contact: <sip:123456@98.99.100.101:2473;rinstance=e14c88765 fa01a20;transport=TCP>

I am not sure if TCP transport is possible with Voxalot, but if TCP transport was being used and you were forwarding only UDP ports, that may explain why port forwarding didn't work. TCP transport is unusual for VoIP, I have not noticed any mention of it in SIP packets before this instance.

I can confirm we support both UDP and TCP