Nithyakumar.R | 1 Feb 08:43 2007

PRACK doubt....


Hi ,

I have doubt in PRACK message..

i)  Proxy  MUST NOT attempt to sent reliable provisional responses.for any
request that contains tag in the To field. That is, a proxy cannot generate
reliable provisional responses to requests sent within the context of a
dialog. 

 As per RFC 3262.. (section 3 .. UAS Behavior)

ii) A UAS MUST NOT attempt to send a 100 (Trying) response reliably.

Can Anyone help me to understand these statement...

i)             why a proxy cannot generate reliable provisional responses to
requests sent within the context of a dialog. ...and

ii)             why UAS MUST NOT attempt to send a 100 (Trying) response
reliably ..

Thanks in advance..

Regards,

Nithyakumar.R

Huawei Technologies India Ltd.,

(Continue reading)

Attila Sipos | 1 Feb 09:51 2007

Re: PRACK doubt....


>>i)             why a proxy cannot generate reliable provisional responses to
>>requests sent within the context of a dialog. ...and

I think this is because once the dialog is up, the call is now end-to-end.
So, reliable provisional responses would be sent end-to-end.

>>ii)             why UAS MUST NOT attempt to send a 100 (Trying) response
>>reliably ..

The 100 Trying does not need to be acknowledged because it doesn't
contain any important information (it is only an acknowledgement).
If the 100 is not successful, then the INVITE will be re-transmitted,
and this will cause the 100 Trying to be re-transmitted.

In other words, the retransmission of the INVITE 
encourages reliability of 100 Trying anyway.

Regards,
Attila

-----Original Message-----
From: sip-implementors-bounces <at> cs.columbia.edu
[mailto:sip-implementors-bounces <at> cs.columbia.edu]On Behalf Of
Nithyakumar.R
Sent: 01 February 2007 07:44
To: sip-implementors <at> cs.columbia.edu
Subject: [Sip-implementors] PRACK doubt....

Hi ,
(Continue reading)

Arif | 1 Feb 09:55 2007
Picon

backward compatibility in 16.4

Hi!
I have a couple of questions about section 16.4 of rfc 3261
which states 
"If the Request-URI of the request contains a value this proxy previously placed into a record-route
header field the proxy MUST replace the request-uri in the request with the last Value from the Route
header field .......
....This will only happen when the element sending the request to the proxy is a strict router. This
rerewrite on receive is necessary to enable backwards compatibility with those elements ...it also
allowws elements following this specification to preserve the Reuqest-URI through strict-routing proxies"

Now:
my point is can I avoid this part based on (1)r there any strict-routing proxies and in which circumstances
these proxies are stil used (2)backward compatiblity with rfc 2543? i mean how many vendors still use 2543
at the moment?

 
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Jeffrey | 1 Feb 10:02 2007
Picon

XCAP Server for list uage implementation


Dear there,

I would like to ask a question about XCAP List Usage implementation. If I
want to implement a XCAP Server providing rls-services document
manipulation, but I want to limit the number of <entry> under the <list>
element, that is per list has a maximum number of 200 <entry>. Is the XCAP
Server allowed to do this? When a XCAP Client want to put a entry but exceed
this limitation, what XCAP Server should respond to client (return an error
code?)
Thanks in advance.

BR,
Jeffrey   

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This email may contain confidential information. Please do not use or disclose it in any way and delete it if
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Igor Vanin | 1 Feb 15:40 2007
Picon

REGISTER - response 200 without Contact

Hello

A softphone sends the REGISTER request (adding or refreshing a binding) to a Registrar and receives 200 OK response.
This response, as specified in RFC 3261, part 10.3, step 8, MUST contain Contact header field values
enumerating all current bindings.

Recently I met a strange server, which is responding to the REGISTER requests (adding or refreshing a
binding) with the 200 OK response *without* any Contact header fields.
I understand that such responses are incorrect, but I must choose the best way how my softphone should
handle them.
Two opposed variants are:
1) interpret 200 w/o contact as signal from the server that it did not registered my contact (i.e. handle it
the same way as 403 response);
2) interpret 200 w/o contact as successfull registration of the contact which the softphone tried to register.
Which of these variants is more correct and user-friendly?

--
With best regards, Igor Vanin, St. Petersburg, Russia
mailto:i <at> gpmail.spb.ru  http://gpmail.spb.ru 

Sachin Srivastava | 1 Feb 15:13 2007

SIP Profile

Can anybody tell what is the meaning of SIP Profile?

Regards
Sachin

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David Oz | 1 Feb 16:20 2007

SIP version of H.249 recommendation

Hi,

I am looking for a SIP RFC/draft for Extended User Input Indication
(like H.249 which works over H.245).
Basically H.249 defines methods for passing user input indications such
as Navigate Left/Right, Activate Selected Item, pointer position (X and
Y coordinates) etc.

Does anyone know about such document?

Thanks,
David Oz
Diego B | 1 Feb 16:53 2007

Re: REGISTER - response 200 without Contact

Hi;
The response must includes a list with the current bindings in the 
registrar server.
If the list is empty ( no Contact headers in the response ) that means 
that there are no
bindings in the server for the AOR you tried to REGISTER.
For example a REGISTER for an AOR with Expires 0 ( Unregister ) will 
result in
a response with no Contact ( assuming there are no other UAs registering 
for the same AOR ).

The response is valid. There may be another problem regarding the 
Registration process.

Regards
Diego B

Igor Vanin wrote:
> Hello
>
> A softphone sends the REGISTER request (adding or refreshing a binding) to a Registrar and receives 200 OK response.
> This response, as specified in RFC 3261, part 10.3, step 8, MUST contain Contact header field values
enumerating all current bindings.
>
> Recently I met a strange server, which is responding to the REGISTER requests (adding or refreshing a
binding) with the 200 OK response *without* any Contact header fields.
> I understand that such responses are incorrect, but I must choose the best way how my softphone should
handle them.
> Two opposed variants are:
> 1) interpret 200 w/o contact as signal from the server that it did not registered my contact (i.e. handle it
(Continue reading)

Brett Tate | 1 Feb 17:03 2007

Re: REGISTER - response 200 without Contact


> Recently I met a strange server, which is responding to the 
> REGISTER requests (adding or refreshing a binding) with the 
> 200 OK response *without* any Contact header fields.

Since it is considered an abnormal situation, the device can act as it
wishes as long as it doesn't continually retry without some reasonable
time delay.

There is likely something related to the Contact which makes it unusable
(scheme, transport, malformed, decoding issue, etcetera) or too low in
priority (q too low, too many contacts, etcetera).

> I understand that such responses are incorrect, but I must 
> choose the best way how my softphone should handle them.
> Two opposed variants are:
> 1) interpret 200 w/o contact as signal from the server that 
> it did not registered my contact (i.e. handle it the same way 
> as 403 response);
> 2) interpret 200 w/o contact as successfull registration of 
> the contact which the softphone tried to register.
> Which of these variants is more correct and user-friendly?

Both of your variants are acceptable.  It is hard to say which is best
since it really depends upon why the Contact is being lost and if the
phone is really still usable.  If some of the Contacts are working,
option 2 might be better.  If none of the phones contacts are working,
option 1 might be better.

(Continue reading)

Alan Liang | 1 Feb 14:45 2007

Re: PRACK doubt....


-----Original Message-----
From: sip-implementors-bounces <at> cs.columbia.edu
[mailto:sip-implementors-bounces <at> cs.columbia.edu] On Behalf Of Attila
Sipos
Sent: Thursday, February 01, 2007 3:52 AM
To: Nithyakumar.R; sip-implementors <at> cs.columbia.edu
Subject: Re: [Sip-implementors] PRACK doubt....

>>i)             why a proxy cannot generate reliable provisional
responses to
>>requests sent within the context of a dialog. ...and

I think this is because once the dialog is up, the call is now
end-to-end.
So, reliable provisional responses would be sent end-to-end.

>>ii)             why UAS MUST NOT attempt to send a 100 (Trying)
response
>>reliably ..

The 100 Trying does not need to be acknowledged because it doesn't
contain any important information (it is only an acknowledgement).
If the 100 is not successful, then the INVITE will be re-transmitted,
and this will cause the 100 Trying to be re-transmitted.

In other words, the retransmission of the INVITE encourages reliability
of 100 Trying anyway.

Regards,
(Continue reading)


Gmane