A call request to the UE-1 containing the MSISDN of the UE-1 as the called party number arrives at the GMSC #1.
On receipt of the incoming call request, the GMSC#1 queries the HSS for routing information.
The HSS provides information including the T-CSI information element that contains information configured for the PNM subscriber, identifying the subscriber as having terminating CAMEL services.
The HSS returns the T-CSI information element to the GMSC#1 in response to the query for routing information (SRI).
The GMSC#1 triggers a CAMEL activity which results in sending a CAMEL IDP message to the GSM Service Control Function (gsmSCF).
The gsmSCF (CAMEL service for PNM) executes the PN UE redirection control logic based on the PN-user's PN configurations as described in clause 6
. The gsmSCF (CAMEL service for PNM) decides to redirect the call request to the default UE of the PN, i.e., to the UE-2.
As a result of the PN UE redirection control logic execution, the gsmSCF (CAMEL service for PNM) to respond to the CAMEL IDP message with a CAMEL CONNECT message containing the MSISDN of the UE-2 as the called party number.
The GMSC#1 initiates the CS call towards the GMSC#2 by sending an Initial Setup Message (e.g. ISUP IAM, BICC IAM, and SIP-I Invite).
The GMSC#2 queries the HSS for routing information and triggers a CAMEL activity to the gsmSCF. The gsmSCF executed the PNM redirection service control logic and decides to forward the request as the UE-2 is the default UE of the PN, so it responds with a CMAEL CONTINUE message to the GMSC#2.
The GMSC#2 continues the redirected call request based on the standard call setup procedures as described in TS 23.018
UE-2 cannot setup the session and generates an error response.
GMSC#2 sends the EventReportBCSM message to the gsmSCF.
The gsmSCF executes the PN UE redirection control logic for the other UE of the next lower priority which in this example is UE-3.
As a result of the PN UE redirection control logic execution, the gsmSCF forwards the redirected initial request containing the MSISDN of the UE-3 as the called party number to the UE-3.