UDP NAT TIMEOUT - Balance 30


Hi guys,

My client have a Balance 30, and he uses a PBX for VoIP Calls.

The problem is when someone try to call him, sometimes the router reject the call, because the dynamic port in NAT is already closed.

The PBX can only re-send the register after 120sec, and I believe that the Router is with a minimal timeout applyed.

Can I adjust the UDP NAT Timeout to 150sec?



Someone? Is very important.


The UDP NAT Timeout is not configurable. Thanks.


Hi Tim,

TKS for your asw… but, what’s the default value?
How much seconds?



I did a search on this Forum and found a post with this info:
UDP Replied - 180 seconds
UDP Un-replied - 30 seconds



I see that too … but I never seem replied/ unreplied

Just Timeout and end point…

Can you know in what case means wich One?

The PBX send a registrar to server, and 120sec after, again…



Hello, is that true? (UDP Replied - 180 seconds
UDP Un-replied - 30 seconds)
What happens to sessions which live longer than the timeouts?


Pepwave Surf SOHO UDP session timeout

Hi Dana,

Tks… but my client don’t use Peplink anymore.
But que timeout of SIP don’t send requests after a minimum of 120s… but we
change for Cisco.



Don’t thinks the PBX for VoIP calls issue are fully descried in the earlier post.

UDP NAT timeout it’s more to the standard value defined for NAT device:

UDP session 30 seconds
UDP established/streaming session 180 seconds
UDP SIP 5060 session 3600 seconds.

The timeout value will keep refreshed back to the default value when traffics is sent via the sessions.Sessions will only being drop/remove when no activity for the session after the timeout value and normally this will happen if the sessions is no longer being used.

Regarding to the VOIP phone issue, i strongly believe the issue is more to the PBX/SIP/VoiP phone configuration issue whereby most of the system should defined with NAT keepalive to refresh the standard session timeouts more than changing the NAT timeout for the NAT devices. You can find some of the related info using the URL below:

Default UDP timeout for Pepwave

Hi Sitloongs,

The thing is, when the client make no more calls in 120s after the
Register with a NAT port, in the time that need an incoming call, the nat
port is closed, and the call cannot be complete.

When we change the router, no more issue happends.

The same think happends on Juniper that have his default on 60s Nat
timeout UDP, but is possible to change, Peplink no.

Tks again.


Sorry as i missed this forum post. Can you please open a support ticket here for us to further confirm the issue ?