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Interesting Issue...VOIP Dropping in Exactly 5 minutes


We just got 3 Primus TalkBroadband boxes.  They work by just plugging into our LAN and then you plug in an analogue phone into the box to talk.  Just like that and you can use it to call people (and receive calls).

They seem to communicate over port 2427 over the Internet.  Primus has a VOIP server that registers our WAN IP associated with the Primus TalkBroadband boxes.  Everything seems ducky on these phones until you talk for 5 minutes; the call gets dropped!

We tested this extensively and no matter what the calls will ALWAYS drop after 5 minutes of conversation.  I talked to Primus support and they think that our firewall (Sonicwall Pro 3060) is dropping the connection due to some "safety" feature.  I opened the firewall port to 2427 but it's no use...still drops the calls after 5 minutes.  Does anyone have any ideas about this?  Much appreciated!
Watch Question

Try adjusting a few settings...

1.  Firewall - > UDP
    Try adjusting the default UDP timeout to a higher number.

2. Firewall - > TCP Settings
    Try adjusting the default TCP connection timeout.


Hi dkwiebe,

The default UDP timeout is set for 30 seconds.  I tried to adjust it higher but the Sonicwall is warning me saying it's not recommended.  Anyways I adjusted it to 60 seconds just to test it out.

Also adjusted TCP timeout from 15 minutes to 30 minutes.  So far calls are still dropped after reaching the magical time of 5 minutes.  :(

Should I crank up the UDP timeout higher than 60 seconds?  Do you know if there's any negative consequences?
Hmmm, I can't get at the sonicwall right now but did you check your "consistent nat" settings?  I'd try consistent nat and some of the other "voip" settings.
Reid PalmeiraTelecom Engineer
Top Expert 2005
Is the sonicwall also acting as the router? if there's another router in there, it may also have some session timeouts. That's where the issue likely lies. if it's a consistent 5 min. it's not connectivity, it's a session timeout somewhere.

Under general settings "enable consistent NAT" should be on
Under SIP settings "enable SIP Transformations" should be checked
     add the 2427 port to the SIP signalling ports for transformation, you may have to enable this on the TCP side as well.
    You may also have to configure the signalling timeout. In many cases the provider will send a "keepalive" packet that keeps the session active. I'm not sure about the ATA's that TalkBroadBand uses, so if all they're doing is initial setup and teardown of calls, then the signalling session times out after five minutes and the call drops.

Link to SonicOS guide: http://sonicwall.com/downloads/Configuring_VoIP_for_SonicOS_Standard.pdf


Found the issue;

Under our Advanced VPN option there's something called "VPN User Authenticaiton Settings".

We added in all the TCP/UDP ports that are used for the VOIP.

It seems to be working now!  Keep in mind that the NAT Traversal is quite important to have enabled as well.

Thanks everyone for your help.

Thanks, enjoy your longer calls!