inline ... -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of varun Sent: Thursday, September 21, 2006 2:50 PM To: [email protected] Subject: [Sip-implementors] Doubts about provisional responses
Hi, I have got some basic questions about the provisional responses in SIP, 180 and 183 specifically. 1> In what cases should 180 be definitely be send as a response.A 180 response can actually contain the SDP info.Assuming that reliability PRACK for provisional responses is implemented, can a two way audio session be established before the caller has got a 200 OK. <sayan> When you want say , the UAC to generate ringback locally , however , any incoming media overrides the local ringback if it arrives from the far end yes it is possible to have a 2 way session, if you include SDP in 183/180 </sayan> 2>Also, 183 is basically used when the call goes across different networks.Why can't simply 180 be used.. How are 180 and 183 different from each other? I mean if the dialog is going to take long so you could have a provisional response which would reset the timer for Invite response. <sayan> There is no hard and fast rule , that 183 will be used when in u interwork with a different network , u may send a 180 if u determine that u need to trigger local ring back at the originating end </sayan> 3>coming to early media, once the caller has send an invite it is ready to receive media( you can play announcements to the caller), what has 183 got to do with early media? <sayan> if you include your SDP in 183 then the you can allow the UAC also to send media , this is used in scenarios where you want to collect inputs from the user through dtmf (example some auth code), before u allow the call to be answered. The offer/answer is often completed with the 18x responses even in normal scenarios , because it helps in avoiding clipping due to race between RTP packets and the 200 OK. From the UAS side the UAC might receive voic packets(RTP) before it has received 200 OK , and hence the UAC side may also start talking , however this will not reach the user as the 200 OK from the UAS side with the SDP answer has not yet reached. </sayan> Some very basic doubts, would appreciate if somebody could spend a few minutes to respond. Regards varun __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
