[VoiceOps] Screwy DSL modem NAT troubles

[Scott Berkman]

My favorite was the Netopia modems ATT/BS was deploying for some time with all their Business DSL circuits (anything with a static IP) that had an “undocumented” ALG that could be disabled via the CLI but not the GUI, but it defaulted to on.  It was of course horribly broken.

 

                -Scott

 

From: voiceops-bounces at voiceops.org [mailto:voiceops-bounces at voiceops.org] On Behalf Of anorexicpoodle
Sent: Tuesday, February 22, 2011 2:28 AM
To: Carlos Alcantar
Cc: VoiceOps at voiceops.org
Subject: Re: [VoiceOps] Screwy DSL modem NAT troubles

 

Ill second Alex's sentiment on abandoning port 5060 and make the traffic look like something other than SIP so the ALG doesn't get triggered. We've been doing this for years, works like a charm. 

Speaking of, if anyone from Linksys, D-Link or any other residential grade router manufacturer is out there listening, you have obviously devoted time and effort to coding these ALG's, why not make them work? I would love to hear why it seems there is a concentrated effort to absolutely break voip with atrociously coded ALG's.




On Mon, 2011-02-21 at 22:19 -0800, Carlos Alcantar wrote: 

 
Linksys ALG seems to break everything sip on the firewall side sonicwall seems to be the death of sip.
 
 
Carlos Alcantar
Race Communications / Race Team Member 
101 Haskins Way, So. San Francisco, CA. 94080
Phone: +1 415 376 3314  Fax:  +1 650 246 8901 / carlos *at* race.com / www.race.com
 
 
 
-----Original Message-----
From: voiceops-bounces at voiceops.org [mailto:voiceops-bounces at voiceops.org] On Behalf Of Carlos Alvarez
Sent: Monday, February 21, 2011 3:08 PM
Cc: voiceops
Subject: Re: [VoiceOps] Screwy DSL modem NAT troubles
 
We go through this all the time with Qwest DSL customers.  Unfortunately I don't have model numbers for you, we stopped documenting things when we noticed that they have all new modems every few months.  However we've had success with having the customer call Qwest and tell them they want to run VoIP phones, the Qwest reps seem to know that as a trigger and send a compatible modem.  I do recall that the best ones are Netopia, and we've had good support when we engage them directly via chat.
 
We also find that modems start going bad slowly after a couple years, and VoIP is the first to get impacted, of course.
 
 
 
Matthew S. Crocker wrote:
> Has anyone else noticed that the latest batch of DSL modems have broken NAT when it comes to VoIP?   I'm seeing stable VoIP customer get broken when the DSL modem is swapped out.  The modem NATs the phones to modem IP port 5060.  So, 10 phones behind the router become one phone to the SBC.  A race condition occurs and phones go in and out of service at random.  It looks like the router is trying to do a SIP ALG but very very broken.
> 
> Do anyone have a DSL modem/router they use that works well with VoIP?
> 
 
 

 

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