Subject: SS7-SIP-SS7 interworking, Early ACM

From: "Ravandhu Hariram" <[email-masked]>
Date: Thu, 13 Jan 2000 16:59:57 -0600

When SIP is used for SS7 to SS7 interworking, which SIP provisional response can
be used to carry an Early ACM which just means that the address is complete and
the called party is being located (an ACM with "No indication" for 'called
party's status indicator' and without any 'optional backward call indicator')? I
can not use '100 trying' as it is not passed end-to-end while going through
proxies. Can I use 183? In that case, what should be the "Session" header field
value?

Any suggestions?

Thanks,
 - hariram

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From: "Adam B. Roach" <[email-masked]>
Date: Tue, 18 Jan 2000 16:08:45 -0600 (CST)

>proxies. Can I use 183? In that case, what should be the "Session" header field

That's generally what I had in mind. My current plan is to map any
of the messages from 180 to 199 to ACM at a PSTN gateway, assuming
we've received an IAM and not sent an ACM, CON, or ANM yet.

Since you will (presumably) not be including any SDP in your message,
you don't use a Session: header.

-- 
Adam Roach, Ericsson Inc. |  Ph: +1 972 583 7594 | 1010 E. Arapaho, MS L-04
[email-masked]   | Fax: +1 972 669 0154 | Richardson, TX 75081 USA