I believe a primary motivation for PRACK was to support preconditions.
(RFC 3312) The need there was to do more than one O/A exchange prior to
answering an INVITE. It turns out that preconditions aren't widely used,
but the mechanism also turns out to be helpful in other cases.
Thanks,
Paul
On 7/25/12 2:25 AM, Aman wrote:
> Vikram,
>
> PRACK is for the reliability of provisional responses, 1XX messages (except
> 100). The reliability of 2xx, 3xx, 4xx, 5xx, and 6xx responses to INVITEs
> is achieved using the ACK method.
>
> This is basically for the critical messages like 180 and 183 i.e when UAS
> wants the conformation from UAC that these 1XX messages are delivered
> properly.
>
> Check out the RFC3262 for more details on this.
>
>
> Cheers,
> Aman
>
>
>
> On Tue, Jul 24, 2012 at 12:48 PM, vikram
> <[email protected]>wrote:
>
>>
>>
>>
>>
>>
>> --
>>
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