[asterisk-users] Same provider - IAX sounds bad, SIP sounds great

Kevin P. Fleming kpfleming at digium.com
Wed Feb 29 09:34:16 CST 2012


On 02/29/2012 09:25 AM, Alejandro Imass wrote:
> On Wed, Feb 29, 2012 at 9:44 AM, Kevin P. Fleming<kpfleming at digium.com>  wrote:
>> On 02/29/2012 08:22 AM, Alejandro Imass wrote:
>>
>
> [...]
>
>> The number of 'plain' SIP endpoints deployed behind consumer-grade NAT
>> devices talking to Asterisk servers on public IP addresses is in the
>> millions, if not the tens of millions. As has already been posted, Asterisk
>> itself handles all the far-end NAT traversal duties necessary for this to
>> work; neither the remote endpoint nor the NAT device need to do anything
>> special, nor do they require any configuration.
>>
>> Rather than post a lengthy exposition on how widespread your network is and
>> how technically astute your people are, you would probably accomplish much
>> more to setup a simple test scenario as has been previously suggested, and
>> if it does not work for you, post the details of the scenario and the
>> failure here.
>>
>
> We use SIP and IAX interchangeably, but had less hassle with IAX. The
> topic of the discussion on this thread was that SIP is so awesome and
> that IAX is a peice of crap. My point of view is that we've had many
> problems with SIP and NAT and that IAX just works great for us, and
> that in *our* experience IAX has worked better for us.
>
> Just to clear my head up a bit: are you supporting the argument that
> SIP is better for Asterisk than IAX?

I have no idea where you got that sort of conclusion. I was making a 
statement to counter your repeated arguments that using SIP behind a NAT 
without special configuration is 'impossible'. It's clearly not 
impossible, it's not even impractical. It is commonplace.

Certainly there are plenty of examples of SIP endpoints working poorly 
behind NAT devices, and replacing that endpoint with an IAX2 endpoint 
curing the symptoms. Invariably, this is caused by the fact that the NAT 
device was attempting to 'help' the SIP endpoint, and failed miserably. 
In every case I can remember, turning off any SIP-specific functionality 
in that NAT device (which is not always possible) allowed the SIP 
endpoint to work as expected.

There are certainly scenarios where deploying a SIP endpoint behind a 
NAT can be problematic; usually, these revolve around deploying a SIP 
*server* behind a NAT, but even this can be handled reasonably well by 
configuration options already present in Asterisk. Deploying SIP 
*clients* behind NATs, talking to a SIP server that is on a public IP, 
is generally trivial and takes no special effort at all.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org



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