Subject: RE: [Sip] Local vs. Remote ringback on 180

From: David Oliver <[email-masked]>
Date: Thu, 20 Jun 2002 10:52:35 -0500

An interesting feature of this scenario is that for incoming calls from the
PSTN, the company IP-switch/PBX will need to generate ringback on behalf of
the callee's no-early-media phone until it answers the call. This would
reasonably be generated by the same subsystem which provides the "press this
button" features, until the IP phone is answered. If the phone is not
answered, the subsystem would provide the opportunity to redirect the caller
to voice-mail, etc.

It seems appropriate to use exactly the same mechanism for IP calls, as this
would simplify the implementation (the PSTN GW would be handled like IP-only
calls), and prevent confusing the caller.

Regards,

David C. Oliver
Principal Engineer
SecureLogix Corp
Email: [email-masked] <mailto:[email-masked]>
Tel:   210.402.9669
Fax:   210.402.6996 

-----Original Message-----
From: Christer Holmberg [mailto:[email-masked]]
Sent: Wednesday, June 19, 2002 2:19 AM
To: Jonathan Rosenberg
Cc: Flemming Andreasen; Mark Watson; [email-masked]
Subject: Re: [Sip] Local vs Remote ringback on 180

Hi,

<...>

I am not sure how it will work on the PSTN side, but let's assume the
following SIP scenario.

I try to call my boss. I reach the company "switch" (which, I guess, in this
case has be implemented as some kind of SIP B2BUA) which sends me a 183
(with
SDP) and start transmitting early media telling me that I have now reached
this company, please wait, press this button for this, press that button for
that etc etc etc. Then, the switch "forwards" the INVITE to the actual SIP
phone I'm calling to. Now, this SIP phone is not able to generate any early
media at all, so it sends a 180 (without SDP). Now I assume the switch could
only forward the 180 to the caller (via the PSTN GW), stop transmitting the
early media, and expect the PSTN GW to generate a local ringback tone, since
the called party has been reached.

Now, one can argue that this is a complicated scenario, which has nothing to
do with the basic SIP etc etc. BUT, from the caller's point of view this is
a
normal session setup. It receives the 183 (with SDP) and 180 (without SDP)
within the same dialog, and has no idea what is happening at the remote
site.

Regards,

Christer Holmberg
Ericsson Finland

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: Ranjit Avasarala <[email-masked]>
Date: Thu, 20 Jun 2002 23:06:23 -0700 (PDT)

Hi David

  I have a query on ur suggestion: like how long are u
goin gto wait i.e "press this button" until phone
answers. say if the person is on phone for a long
time, then what should be the solution

Ranjit
--- David Oliver <[email-masked]> wrote:
> From: Christer Holmberg
> [mailto:[email-masked]]
> Sip mailing list 
> https://www1.ietf.org/mailman/listinfo/sip

__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com