One-Way Audio
 

Calls through Voxalot often are only one-way audio. Direct calls to my VSPs are okay.

Symmetric NAT is off, and I'm using proxy failovers on an SPA-3000.

Any thoughts?

One-way-audio
 

Usually, one-way-audio is due to NAT problems. The reason is that your VSP doesn't know your public IP address so it can not establish a correct path to the RTP packets in both directions. There are several reasons for this kind of problem, but you can try do the following to solve it:
1 - Configure properly a STUN Server in your device;
2 - Configure port forward in your router (5060 to SIP and something else to RTP packets). In this case you don't need a STUN server, but you can also use it;
3 - Use Symmetric NAT in Voxalot account. This option introduces some delay in the voice packets but usually not noticeable. I should say that I'm using Symmetric NAT in a transatlantic scenario and the delay introduced by such configuration is almost unnoticeable.
Regards,

Direct calls to my VSPs are okay, though.

That doesn't mean your NAT settings are correct.

If your SPA-3000 is behind a NAT router the problem may be solved by settings the following:

(under SIP tab)
Handle_VIA_received: yes
Handle_VIA_rport: yes
Insert_VIA_received: yes
Insert_VIA_rport: yes
Substitute_VIA_Addr: yes
Send_Resp_To_Src_Port: yes
STUN_Enable: yes
STUN_Server: stun.voxalot.com:3478 (or any STUN server such as 'stun01.sipphone.com:3478' or 'stun.sipgate.net:10000')
NAT_Keep_Alive_Intvl: 179

(under Line_1 and Line_2 (or PSTN_Line) tabs)
NAT_Mapping_Enable: yes
NAT_Keep_Alive_Enable: yes
NAT_Keep_Alive_Msg: (this setting should be blank)
NAT_Keep_Alive_Dest: $PROXY
Register Expires: 3600

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If you prefer to operate your ATA without a stun server make the following changes to the above settings:

1. Forward the SIP ports and the RTP port range from the router to the ATA.
2. Set "STUN Enable:" no
3. Set "NAT Keep Alive Enable:" no
4. In order for the ATA to know it's public IP address, make sure it is registered with at least one SIP registrar, or enter your public IP address into the "EXT IP:" field).

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If the problem persists it may indicate your ATA is behind a Symmetric NAT device. Here is a strategy that will adapt to whatever Symmetric NAT status is present:

1. Use settings shown above in bold type.
2. In your ATA set "STUN Test Enable:" = yes.
3. In your Voxalot account set "Symmetric NAT Handling" = yes

When active, Voxalot's "Symmetric NAT Handling" option routes the voice packets through a Voxalot proxy. Note; even when you set "Symmetric NAT Handling" = yes Voxalot will not activate this option unless it detects that your ATA has disabled NAT mapping. See the below quote from the Linksys ATA manual:

"If the STUN Enable feature is enabled and a valid STUN server is available, the Linksys ATA can perform a NAT-type discovery operation when it powers on. It contacts the configured STUN server, and the result of the discovery is reported in a Warning header in all subsequent REGISTER requests. If the Linksys ATA detects symmetric NAT or a symmetric firewall, NAT mapping is disabled."

This is not a problem in your config, but a problem in Voxalot's US servers.
Martin has fixed it in the past, by restarting some services in those servers.

It started again a couple of days ago.

pleeeeeeeeeeeeeeease!

Cyberian75,

Are you still experiencing one way audio when using one of the US servers? If so try the following steps.

Turn on "Symmetric NAT Handling" in your Voxalot account.

In your SPA-3000
1. set NAT Mapping Enable: no - (this is signals Voxalot to engage it's "Symmetric NAT Handling" function, otherwise Voxalot will not use "Symmetric NAT Handling" even if you have enabled it)
2. set Use DNS SRV: no
3. set Proxy: proxy01.us1.voxalot.com
4. set Outbound Proxy: proxy01.us1.voxalot.com
5. change "SIP Port:" to a different port (otherwise your ATA may accept an incoming call from the previous proxy until registration has expired, that could be up to 1 hour)
6. set Use Outbound Proxy: yes
7. set Use OB Proxy In Dialog: yes

In your router you may have to disable ALG as this function may re-enable NAT Mapping within the SIP packets, thereby disabling Voxalot's "Symmetric NAT Handling".

Thanks, but I gave up on using Voxalot.

Re-started RTPProxy services on both US servers. Please let me know is this has addressed your problem.

Martin, thank you very much.
I will do a lot of tests today and then I will post here the results.
regards
Jose Pinto