[Kamailio-Users] Loose Route / Re-Invite

[Klaus Darilion]

Hi Brandon!

This is my pragmatic approach:

During dialog-creating transaction (INVITE, SUBSCRIBE) I decide if a 
clients gets NAT-traversal* or not. Thus result will be stored in a 
record-route cookie (add_rr_param()).Therefore, when dooing loose_route 
I will check the content of this parameter and therefor apply same 
strategy to in-dialog requests.

* perform NAT traversal always, unless I know for sure that the client 
does not support symmetric SIP. For doing NAT traversal you can either 
use fix_nated_contact() - which is not standard conform but works - or 
use the new add_contact_alias/handle_ruri_alias (kamailio 3.0: 
http://sip-router.org/docbook/sip-router/branch/master/modules_k/nathelper/nathelper.html#id2806306)

regards
klaus


Brandon Armstead wrote:
> Hello everyone,
> 
>    I'm just curious as to see what some of you guys do in regards to 
> handling a Re-Invite that comes back downstream to a NATTED UAC.
> 
> For example, call scenario:
> 
> UAC -> Kamailio (Fix Nated Contact) -> PSTN
> 
> Re-Invite Occurs:
> 
> PSTN -> Kamailio -> UAC
> 
> UAC (200 OK w/ NAT RFC1918 contact) -> Kamailio (branch flags at this 
> point are not notifying of NAT, due to the downstream direction of the 
> INVITE, so RFC1918 address exists, but does not fix_nated_contact) -> PSTN
> 
> PSTN does not appropriately ACK.
> 
> 
> So, what are your guys solutions for solving this problem?
> 
> Is the best way to add an attribute onto the contact header sent in 
> original INVITE?  Are there other ways of handling?  What is the best, 
> cleanest method.  Possible to handle with AVP's?
> 
> Thanks in advanced for all of your input!
> 
> Sincerely,
> Brandon
> 
> 
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