iax/sip traffic

Unanswered Question
May 14th, 2008
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HI ,

I want to allow iax traffic through the ASA 7.2.2.

Is there a inspect available for that .

We do have sip inspect also I want to know the adv of passing iax traffic rather than sip traffic through the ASA


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Overall Rating: 4 (1 ratings)
elparis Wed, 05/14/2008 - 05:23
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  • Cisco Employee,

Hi Raj,

IAX, and more specifically, IAX2, which is the version of IAX currently is in use, does not need any type of inspection because audio and signalling are unified, unlike SIP. To allow IAX traffic through the ASA you only need to allow traffic to UDP port 4569 in your inbound ACL (plus the static to forward this traffic to your PBX).

Regarding the advantage of passing IAX2 traffic instead of SIP traffic, well, that depends on what your PBX uses. If your PBX only uses SIP then there is no point in letting IAX2 go through. If your PBX can use both SIP and IAX2 to talk to other PBXs/devices the IAX2 seems like a better option.

Take a look at this good comparison between the two written by one of the authors of the IAX protocol:


This other link touches on some points regarding NAT and IAX:


Hope this helps.


Eloy Paris.-


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