First off, questions like this belong on the sip-implementors list.

  
-----Original Message-----
>From: Hrishikesh Saria [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, April 26, 2001 2:17 PM
>To: [EMAIL PROTECTED]
>Subject: [SIP] Problem with ACK through proxy
>
>
>hi,
>    i am receiving a Record-Route header in the 200 OK response. The Route
header in the 
>ACK is being constructed using this. But the ACK is not reaching the callee
, though it is 
>reaching the proxy. But if the other person sends a Contact header in the
200 OK and that 
>is added at the end of the Route header in ACK  , the ACK  is reaching the
callee. If the 
>Contact header is not present, what is being done ... this is wrong, i
agree... (but it 
>works) ... is that i am extracting the IP address of the callee's system
from the 'c=...' 
>of the SDP. 

Egads! That is extremely bad. Don't do that. It won't work for softswitches,
for example, and for a host of other scenarios. 

>    So , i have 2 questions:
>    is the contact header mandatory in 200 OK for invite?

As Brett indicated, it is now mandatory for rfc2543bis. Most of the mature
implementations available today are already doing this.

>    if not , what is the proper solution to the above problem? i,e,.
without having to 
>look at SDP header...

The proxy will get the request, and that request will not have a route
header. So, it should do its normal request processing. This processing will
look at the request URI, and figure out where to send it. If the proxy
record-routed correctly, that request URI should cause the proxy to route
the request to the called party. By record-routing correctly, it means the
proxy should have inserted a URI into the record route which routes to the
next hop it sent the request to. The most obvious way to accomplish that is
to copy the request URI of the incoming request into the RR, adding an maddr
and port that point to the proxy. 

-Jonathan R.
---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[EMAIL PROTECTED]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com
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