Sanity check - UDP session timeout

[haci]

As per title we've recently had a new phone system installed by a third party, and had issues with phones not ringing and other issues.

They are insisting we increase the UDP session timeout on our firewall to 11 minutes (their phones register every 10 minutes).

 

I've not read into it a huge amount but my understanding is most phone systems have a setting UDP keep alive which essentially has the handset send a packet every x seconds to keep the session live.

I would assume that using that would be preferable to extending the UDP session timeout from 30 seconds to 11 minutes for every single UDP session on the network.

 

I feel a little bit like I'm being made to look like a blocker and maybe I am being overly cautious but ultimately if it all goes Pete Tong its me that will be to blame.

 

am I needlessly worrying or should I pitch my tent on this hill?

[Wave9_Lee]

You could either set the timeout to 11 mins to see if that fixes the issue, or you could ask them to change their polling interval. Our voip is set to 10 seconds...

 

11 minute session timeout is a very long time. Think most fw vendors recommend between 120 and 300 seconds. You can sometimes set the timeout rule at application level to avoid resource impacts if globally set in large school

[PaddyNewman]

We have never changed our UDP timeout from Cisco standard. We've got every VoIP provider under the sun on our end and it's never been too much of a problem. Seems an odd way to do it rather than just send shorter timers from the devices..

[haci]

Thanks for confirming both of you, it was one of those moments I said no but then doubted myself.

 

Thanks for reassuring, they are now making some changes to the handsets which should resolve the issue.