Mostly just reference material for me:

Possible values:

• 0 (ORIGINATING_SESSION)
• 1 TERMINATING_REGISTERED
• 2 (TERMINATING_UNREGISTERED)
• 3 (ORIGINATING_UNREGISTERED

In the past I had my iFCs setup to look for the P-Access-Network-Info header to know if the call was coming from the IMS, but it wasn’t foolproof – Fixed line IMS subs didn’t have this header.

            <TriggerPoint>
                <ConditionTypeCNF>1</ConditionTypeCNF>
                <SPT>
                    <ConditionNegated>0</ConditionNegated>
                    <Group>0</Group>
                    <Method>INVITE</Method>
                    <Extension></Extension>
                </SPT>
                <SPT>
                    <ConditionNegated>0</ConditionNegated>
                    <Group>1</Group>
                    <SIPHeader>
                      <Header>P-Access-Network-Info</Header>
                    </SIPHeader>
                </SPT>                
            </TriggerPoint>

But now I’m using the Session Cases to know if the call is coming from a registered IMS user:

        <!-- SIP INVITE Traffic from Registered Sub-->
        <InitialFilterCriteria>
            <Priority>30</Priority>
            <TriggerPoint>
                <ConditionTypeCNF>1</ConditionTypeCNF>
                <SPT>
                    <ConditionNegated>0</ConditionNegated>
                    <Group>0</Group>
                    <Method>INVITE</Method>
                    <Extension></Extension>
                </SPT>
                <SPT>
                    <Group>0</Group>
                    <SessionCase>0</SessionCase>
                </SPT>             
            </TriggerPoint>