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Contents

SMS CALL FLOW BETWEEN GSM AND CDMA NETWORK

The above fig illustrates sms flow between GSM and CDMA network.CDMA network uses the concept of sudo HLR for SMS routing.
·         MOBILE subscriber from GSM network initiates an Originating SMS to be delivered to a CDMA network.
·         Now MSC A forwards the SMS packet to SMSC-A (MO-FORWARD-SM).
·         ROUTING USES SCCP CALLING ADDRESS: GT OF MSC AND
SCCP CALLED ADDRESS GT OF SMSC(SERVICE CENTRE ADDRESS)
·         INFORMATION CONTANS: SMS,A NUMBER, B NUMBER, SC ADDRESS
·         SMSC AFTER CHECKING BASIC AUTHENTICATION, RESPONDS WITH MO-FORWARD-SM-ACK
·         ONCE THIS ACK REACHES TO HANDSET, ORIGINATOR KNOWS THAT HIS MESSAGES HAS BEEN SUBMITED INTO THE SMSC
·         NOW SMSC NEEDS TO KNOW THE LOCATION OF SUBSCRIBER B. SO SMSC INITIATES SRI QUERY(SEND ROUTING INFORMATION). SMSC SENDS THE PACKET TO GW MSC-A, WHICH FURTHER FORWARDS TO CDMA-GWMSC.
·         CDMA GWMSC FORWARDS THIS PACKET TO PSEUDO-HLR (RESIDES WITHIN SMSC-B).
·         PSEUDO-HLR RESPONDS WITH A FAKE-IMSI, FAKE-VLR ADDRESS(GT OF SMSC-B)
·         SMSC DOES NORMAL MT-FSM TO THIS FAKE-VLR GT RECEIVED IN SRI-ACK.
·         SMSC-B RESPONDS TO THIS MT-FSM WITH MT-FSM-ACK.
·         SMSC-A KNOWS THAT ITS MESSAGE HAS BEEN DELIVERED AND INFORMS ORIGINATOR SUBSCRIBER IF “STATUS-REPORT” HAS BEEN REQUESTED.
·         SMSC-B NEEDS TO KNOW WHERE ITS CDMA SUBSCRIBER B IS LOCATED
·         SO SENDS SMS-REQ MESSAGE TO LOCAL HLR.ONCE THE LOCATION OF SUBSCRIBER IS KNOW
·         SMS IS DELIVERED USING MT-SMDPP MESAGE.
 

 cdma gsm call flow