Archive: No sound over VPN tunnel

[Tom Wellige]

The following forum topic is restored from the Swyx Forum Archive (2007-2014)

 

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2007-08-24 14:36:55, petjez
 

Hello,

we use SonicWALL firewall's in our company. We use these devices also for site-to-site VPN. Between 2 of our sites i build a VPN and everything looks okay. I can reach windows shares over the tunnel and browse to the Swyxserver shares. I can also logon my Swyxphones to the Swyxserver (6.02). When i call a number on the other side of the VPN (or the other way arround) i get the ringer. When i pickup i can see i'm connected. But there is no sound at all !!!

I've tried another type of VPN and this works oke. So my guess is that things in the SonicWALL are blocked or someway disturbed. Maybe the end-to-end communication does not work properly.

Can someone give me advice how to troubleshoot this? I've turned on all logging in the SonicWALL devices, but i don't see anything strange. Except for the fact the the phone on the remote location is logged on with H323 instead of SIP!!!

Regards,

Patrick

 

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2007-08-24 14:53:06, morten.rokosz
 

Enhanced or Standard OS?

You could have a quick look at this thread to see if you get something from it: Remote Users and Cisco

 

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2007-08-24 15:02, petjez
 

Enhanced OS, i will check out your link.

Thanks.

 

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2007-08-24 15:08:16, petjez
 

VPN tunnel is transparent. I can ping the other Swyxphone over the VPN tunnel. So i figure the sound much works also?

 

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2007-08-24 15:31:27, morten.rokosz
 

We have had some bad experiences with Enhanced OS and SwyxPhones. No exactly what you described, but using TZ150 terminated to an PRO series with Enhanced OS we lost mediastreaming after some time, but only one way. We had to change to Standard OS box to make it work.

You could try this as well; Log on to the Swyxphone using your browser like this https://ipofphone , and select Administration, PW = 123456 if not changed. Go to Network -> Quality of Service and uncheck both Layer 2 and Layer 3.

My guess is that this will not help, but try this before changing the Sonicwall for other brand.

 

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2007-08-24 15:38:45, petjez
 

Morten,

i will open a support call with SonicWALL. There is some VOIP support in the device, so i hope they can help me.

Do you know wich ports or protocols are used for the phone-to-phone mediastreaming?? I can ask SonicWALL support if it is possibel to use these ports / protocols in some kind of transparent mode.

Regards,

Patrick

 

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2007-08-24 21:37:04, morten.rokosz
 

petjez wrote

Do you know wich ports or protocols are used for the phone-to-phone mediastreaming??

Have a look at KB 2308

 

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2007-08-25 11:00:59, bveldhuis
 

This problem is caused by TCP time-out on the sessions.
Once the phone registeres with the swyx-server a session is created in your firewall devices. As long as that session is there you will be able to have sound.
As soon as the TCP session for the registration is dropped in the firewall your sound will go as well.

Cause: The audio stream comes on a different protocol, and to the firewall 'with-out-notice' (with a user requesting it) and hence it will drop the audio.

To solve this:
Disable TCP-SYN check on your firewalls. preferable only for the VPN's.
On juniper this can be achieved by:

- unset flow tcp-syn-check-in-tunnel

I don't know what the command on Cisco Pix it, but should be something similar

 

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2007-08-25 11:19:11, morten.rokosz
 

For details on Cisco look at this thread: Problem with L420e in a remote office

 

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2007-08-28 15:07:37, petjez
 

Hi,

this issue is fixed by altering the MTU size if the SonicWALL's WAN interface. The support guys of SonicWALL fixed the problem. I found the best MTU size by pinging a public IP number with the parameter -l <packetsize>. 'ping -l 1490 4.2.2.2'. The lowest possible MTU size did the trick.

Thanks for all the thinking.

Regards,

Patrick

 

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2007-08-28 15:25:39, morten.rokosz
 

Thanks Patrick. Then our issue was something else, because we lost sound one way after a while, not from the start of the conversation.

 

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2009-05-28 09:45:29, SWYXITGOOD
 

I got no sound over a VPN tunnel, then one-way sound using compression - (2 x Draytek 2600 VPN)

Yet if I conference that remote user into another conversation we all can hear eachother fine

 

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2009-05-28 09:45:29, SWYXITGOOD
 

(sorry my setup always makes dual posts !)