[asterisk-users] nat and qualify questions

[Alyed Tzompa]

from

http://www.voip-info.org/wiki/view/Asterisk+sip+qualify

						> qualify=xxx|no|yes

>where XXX is the number of milliseconds used. If yes the default timeout is used, 2 seconds.

>If you turn on qualify in the configuration of a SIP device in sip.conf, Asterisk will send a SIP OPTIONS
command regularly to check that the device

>is still online. If the
device does not answer within the configured (or default) period (in
ms) Asterisk considers the device off-line for future calls.

What happens if you use nat=yes is that Asterisk will consider the IP
for communicating with the SIP user agent (UA) as the IP from where the
SIP invite comes from instead of taking the one included in the SDP
message. Hence if you are using phones inside a LAN this 2 addresses
will be the same, but if your SIP UA is outside they will not.

Having all your phones set with nat=yes and qualify =yes, will not
affect the behaviour of your phones if your network is not really full,
but will be a bad and dirty way to do it :)

Alyed 

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As
far as i know qualify=yes will increase you network traffic, this will
make asterisk to communicate with all sip friends every X seconds, not
sure the default value.

On 8/1/06, 
BerkHolz, Steven <StevenBerkHolz at tescogroup.com> wrote:Are there any 
problems with always having nat=yes and qualify=yes?   We just opened up 
our server to be accessible to SIP from the internet. (used to require 
VPN)   I had to set the SIP 
setting for my test softphone to nat=yes and qualify=yes. This makes 
sense.   Some of these phone 
will never leave our building. Some of these phone 
will come and go. (laptops)   Is the any negatives 
to just have all phones set to nat=yes and qualify=yes? If not, why is it 
not the default?  

Thank You,Steven 
BerkHolz
- MCSA 
- MCSE -
Manager of Information Systems
TESCO Group 
Companies
Fax. 248-836-5101
www.TESCOGroup.comBoard member 
of
www.glimasoutheast.org

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