[asterisk-users] Purpose of qualify=yes

[Steve Totaro]

On Wed, Sep 15, 2010 at 8:20 PM, Chris Owen <owenc at hubris.net> wrote:
>
> We have a tenant who has been having issues with a congested connection and in trouble shooting it we've noticed that there seems to be a lot of SIP traffic even when none of the phones are doing anything.
>
> We've determined that this traffic is mostly INFO packets generated by setting qualify=2000.   I understand that 2000 ms is the default value for the qualification parameter but what I'm unclear on is exactly what the purpose of having asterisk qualify the phones is.
>
> I know that in a NAT situation, qualifications can help keep UDP sessions open in the firewall but in our case most phones are not behind NAT.
>
> I realize qualifying phones is also how asterisk keeps track of who is available for things like BLF but surely it doesn't need to do that every 2 seconds to keep the BLFs reasonably current.
>
> So I guess my question is what is the real purpose of the qualify setting in a non-NAT situation and can one safely set the qualification as something higher.   I'd think something like 15 seconds would be more than enough for BLFs and the like.
>
> Chris

Try it without qualify=yes.  I have had phones setup over VSAT links
and qualify=yes was a problem.  Ping times averaged ~700ms from
Equinix to Baghdad, but with packet loss and a wide range (jitter) in
ping times, I constantly had phones jumping between "Reachable" to
"Unreachable"

I kept upping the value of the qualify statement which helped, but I
finally just dropped it because everything was on the same subnet, and
OpenVPN subnet.  It worked just fine besides high jitter buffers and
people needing an understanding that there would be a delay so they
wouldn't step on each other as they spoke.

Thanks,
Steve T