[SIPForum-discussion] The process sequence

Shmulik Basan sbasan at 10levels.com
Fri Jun 19 22:34:55 UTC 2009


No, it's not needed.
183 session progress define the media and therefore RTP can pass so user
will hear the ringback tone as media.
When remote side answer the call the call will continue in the same MEDIA as

Usually, in order to save BW then 183 will (and should) reserve the path and
define the media and 180 will alert the other side to start playing
"ringback" tone locally

Shmulik Basan 

-----Original Message-----
From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Karthik Ramiya
Sent: Friday, June 19, 2009 11:42 AM
To: neeraj.jain at samsung.com; Mike Jiang; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] The process sequence


   But is 180 ringing really needed when we get a 183 in the firstplace??


From: discussion-bounces at sipforum.org [discussion-bounces at sipforum.org] On
Behalf Of NEERAJ JAIN [neeraj.jain at samsung.com]
Sent: Friday, June 19, 2009 11:48 AM
To: Mike Jiang; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] The process sequence

Hi MIke,

183 session progress is generaly used when user is intrested in resource
reservation according to 3GPP spec. Genrally 183 and PRACK is used to do the
media negotiation before user is alerted. So it always comes before 180



------- Original Message -------
Sender : Mike Jiang<mike.jiang at andersontaylor.com>
Date : Jun 19, 2009 02:35 (GMT+09:00)
Title : [SIPForum-discussion] The process sequence

Hi All,
      One quick question: I was wondering if the Ringing (180) is always
occurring ahead of the Session Progress (183).
      In my case, the 183 response always happened before the 180 happened.


      Mike J.

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