[SIPForum-discussion] How to connect an open IMS core and AS

[Tomasz Zieleniewski]

Hi,

OSIMS is the implementation of the IMS core network which provides so
called service control model specifying how control layer interacts with
service layer through ISC interface.

Here is a overall procedure which you must support in your softswitch:

When SIP request reaches S-CSCF, S-CSCF  determines the public user identity
(IMPU) associated with this request. It determines IMPU by examining the
P-Served-User field
or if it is not present, it examines the P-Asserted-Identity header. After
this S-CSCF determines
if request originated from the network or from the application server. If
request is comming from the
network then S-CSCF uses IMPU to construct an ordered list of initial filter
criteria.
On the other hand if request is comming from AS such list already exists.
S-CSCF
continous processing the request according to any unexecuted initial filter
criteria matches.
If there is a match S-CSCF uses AS URI and forwards the request. S-CSCF uses

Route header to force appropriate request routing, it puts AS URI as the
topmost value
and its own URI in the second one ir order to assure that the request will
return to it after
processing in AS. When the request passes all possible application servers
S-CSCF
determines the destination address using standard SIP routing procedure.

Kind regards,
- Tomasz Zieleniewski
------------------------------
ICT Backyard - http://ictbackyard.com


2010/1/27 Murali Vuppandla <mvuppand at cisco.com>

>  Tomasz,
>
> Thanks for your quick reply.
>
>
>
> I’ve gone through it. I couldn’t understand few steps mentioned in that.
> Just wanted to know if any other method is there to do it.
>
>
>
> Here, Application server refers to the soft switch which performs all the
> call processing activities. We are just trying to support AS features.
>
>
>
> Pls. let me know if any other alternative is there.
>
>
>
> Regards,
>
> Murali.
>
>
>
> *From:* Tomasz Zieleniewski [mailto:tzieleniewski at gmail.com]
> *Sent:* Wednesday, January 27, 2010 8:22 PM
> *To:* Murali Vuppandla
> *Cc:* discussion at sipforum.org
> *Subject:* Re: [SIPForum-discussion] How to connect an open IMS core and
> AS
>
>
>
> Hi,
>
> Answer You are looking for:
> http://ictbackyard.com/archives/316
>
> Kind regards,
> - Tomasz Zieleniewski
> ------------------------------
> ICT Backyard - http://ictbackyard.com
>
>  2010/1/27 Murali Vuppandla <mvuppand at cisco.com>
>
> Hi All,
>
> I  installed an open IMS core and ran a basic call with IMS clients
> installed on two different systems. Now, I’ve to connect this IMS core to
> the Application Server.
>
>
>
> Could anyone give me the detailed steps to do this ??
>
>
>
> Regards,
>
> Murali.
>
>
>
>
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