[cisco-voip] ATA using SIP with NAT/Registration problem / SIP 406 Not Acceptable

[Karim Rahmani]

Hi everyone, 

 

I have a little issue with one of my customers:  Since some months they are using NAT with a Cisco7301 router in order to translate ATA ip addresses from an internal network to a public address (PAT is used). These ATA are registering to an external SIP server according to this scenario:

 

ATA-----------Cisco7301_with_NAT_(LNS)------------Sip_Server

 

The strange thing is that it was working properly during many months but when the number of the registered ATA boxes reached 42, some problems has been met =>  The ATA boxes could not automatically register although there is an entry in the translation table for these ATA.

The only way to make new ATA box to register is deleting its entry in the nat table and reboot it.

 

The 'debug ip nat sip' let us think the NAT is done correctly and in a wireshark capture we can see SIP 406 Not Acceptable answers to the registration request.

 

SIP 406 Not Acceptable :

This response indicates that the requested resource is capable of generating only responses that have content characteristics not acceptable as specified in the accept header of the request. The SIP gateway does not generate this response. After receiving this response, the gateway initiates a graceful call disconnect and clears the call.

 

Do you know if there is any restriction or limitation regarding the number of SIP sessions supported by the NAT? I made some bugs researches but I did not manage to hit one?

I think I will open a TAC case but if someone has ever met this symptom it would be great. If not I will share the TAC case conclusion if we fix this issue.

 

7301 IOS is c7301-spservicesk9-mz.124-15.T4.bin

 

Thank you very much for your ideas.

 

K. Rahmani
Support Client , Telindus France
10 , avenue de Norvège , ZA de Courtaboeuf 1 BP 742
91962 Les Ulis cedex France
Mailto:karim.rahmani at telindus.fr <blocked::BLOCKED::mailto:karim.rahmani at telindus.fr> 
Telindus. Change things your way. http://www.telindus.fr <blocked::BLOCKED::http://www.telindus.fr/> 



 

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