???? wrote:
> Hi,
> I am not sure of your use case but I think your requirement could be
> achieved if you send INVITE/ACK without any content (SDP media or something
> else). This will make session hence end-to-end dialog for you.
I beg to differ. If you send the INVITE without any content then it is
an offerless invite. In that case the UAS is obligated to send an offer
in its response.
Of course it *could* send an offer with no media, but most UAs would
offer media in that case. And of course if it did offer you media you
could accept the call but refuse the media, which would arrive at the
same place that sending an offer with no media would.
But if you intent going in is to establish a call with no media, then
you are better off being explicit about it. Take a case where the call
is forked to devices with different capabilities - e.g. a phone that
only does voice as well as a device that does this
session-mode/page-mode thing. If you make your offer then the phone can
refuse the call. If you make an offerless invite then it will most
likely respond.
Paul
> Vipul Rastogi
> Engineer, Business Management Team
> Telecommunication Network Business
> Samsung Electronics CO, LTD
> Suwon P.O.BOX 105, 416
> Korea 442-600
> MO 010-9530-0354
> ----- Original Message -----
> From: "Vikram Chhibber" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Wednesday, November 14, 2007 11:15 PM
> Subject: [Sip-implementors] page-mode instant-messaging question
>
>
>> Hi,
>>
>> I want to perform page-mode instant messaging (using SIP MESSAGE) on a
>> dialog created by INVITE. This INVITE I want for establishing a dialog
>> on which I can send SIP MESSAGE only and there will be no media. I do
>> not want msrp either.
>> In this case, how should I construct offer and then answer SDP?
>> SDP with no m line should be fine but is there some media description
>> defined for this purpose?
>>
>> Thanks,
>> ~Vikram
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>>
>
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