Subject: RE: 180 to ACM Mapping

From: John Hearty <[email-masked]>
Date: Thu, 18 Feb 1999 17:03 -0600 (CST)

>I guess where the trouble starts is what does a
>180 Ringing response really mean when inter-working
>with the PSTN is encountered and how should a
>UAC react upon reception of one?

 For that matter, how should an originating UAC react in a pure SIP
environment when it gets a 180?  I have heard SIP phones are already
available that locally generate ringback in this scenario.  This makes
sense, and if things are uniform, the PSTN gateway (acting like a UAC
on behalf of the PSTN caller) should also generate ringback when it
gets a 180.  Hence, it would seem some other 1xx response that triggers
an ACM for one way voice path cut through is needed.

John Hearty
MCI Worldcom