In GSM phase 2, the MS is able to command the SMSC . Subscriber A, for example, can cancel an SM that has not yet been delivered to subscriber B, or can request a status report about whether the SM was delivered to the subscriber or not. These commands appear as ordinary SMs to the network, but the SM data contains a field indicating the message type. This message type is extracted from the SM for charging and statistical purposes.
The network indicates the result of the command to the subscriber by Status Report. This message type is extracted from the SM for charging and statistical purposes.
MO-SM with Status Report request
When subscribers send mobile-originating SMs, they can request information on whether the SM was delivered to the destination MS, or not. It is possible if the Status Report Request field is set in the mobile-originating SM by the sender. If the SM was delivered, or cannot be delivered at all, Status Report is sent to the originator of the SM indicating the result of the delivery. The information about whether the Status Report request is set in the MO-SM is carried from the SMS application to the charging application, and in this case the SMMO CDR can be generated with the 'Mobile originated short message status report requested' SMS type value. It means that if the optional PRFILE parameter
MO_SM_STATUS_REP_REQ is turned on, you are able to apply different charging for MO-SMs in which Status Report is requested.
Figure 7. SMS command and status report
For related information, see SMS status report .
The relevant parameter can be found among SMS-related general parameter file
(PRFILE/FIFILE) parameters .
SMSC address on the MSC-SMSC interface
The SMSC address used by the MS can be sent to the SMSC on the TCP/IP interface.
If an SMSC number modification happens in the MSC due to different SMS applications (such as bank information), the new SMSC address is used for routing purposes. However, the old SMSC address is also needed in the StatusReport case, because the mobiles can only understand the SMSC addresses stored in them, that is, the ones that were used in SM sending.
The MSC sends the SMSC address given by the subscriber to the SMSC on the TCP/IP interface. It does not affect the MSC-SMSC interface because this parameter was implemented on the interface already for future use.
With SMSC address sent to the SMSC, you do not need to use predefined SMSC addresses because the StatusReport is appropriate even if you have several SMSC addresses.
With the help of this functionality you can also use the networked SMSC solution: several SMSCs can be connected to the network with a single SMSC number, resulting in messages being routed according to destination number to the nearest SMSC. Note SMSC MSC SMS-Command SMS-Command:
What happened to the SM I sent to my friend?
SMS-StatusReport SMS-StatusReport:
Your SMS was delivered at 16:51 pm.
1 2
3 4
You can use this feature if you have the SMSC connected through MAP (in the VMSC function), and also if you have the SMSC connected through SMRSE with TCP/IP. MAP version 3 is needed for this functionality. For details refer to the feature activation instructions ofFeature 1165: Short Message Services, GSM Phase 2+ Enhancements .
In MO-SMS the SMSC-GT-1 represents the SMSC address given by the subscriber, and the SMSC-GT-2 represents the SMSC address given by the VMSC. If the SMSC address is changed in the VMSC, then the new SMSC address (SMSC-GT-2) is used on the SCCP level for routing purposes, but the MS-defined address is sent in the MO_FORWARD_SM MAP operation. Number modification can also take place in the SMS-IWMSC. In this case the number given by the subscriber is sent to the SMSC (SMSC-GT-1), and the new address (SMSC-GT-2) is used only for routing purposes.
Figure 8. Successful MO-SM transfer with SMSC-GT-1 parameter
In MT-SMS the SMSC-GT-1 represents the SMSC address given by the MS, and the SMSC-GT-2 represents the physical SMSC address that is used by the subscriber.
The transfer of the SMSC address given by the subscriber to the SMSC causes changes in the VMSC, SMS-IWMSC, and SMS-GMSC .
MS CP_DATA VMSC IWMSCSMS SMSC CP_ACK number modification MAP_MO_FORWARD_SM (SMSC-GT-1)
SMSC-GT-2 on SCCP level for routing
SC_RP_MO_DATA (SMSC-GT-1) SC_RP_MO_DATA_ACK MAP_MO_FORWARD _SM_ACK CP_DATA CP_ACK
Figure 9. Successful MT-SM transfer with the SMSC-GT-1 parameter
1.5
SMSC Alert
The GSM system uses Alert-SC to inform the SMSC (which acts as a store and forward centre for SMs), that a subscriber has become available again and can now receive new messages. There are two cases in which the system knows when to send the Alert-SC:
SMSC GMSCSMS- HLR VMSC MS SC_RP_MT_DATA (SMSC-GT-1, SMSC- GT-2) MAP_SEND_ ROUTING_INFO_ FOR_SM (SMSC- GT-2 MAP_SEND_ ROUTING_INFO_FOR_ SM_ACK MAP_MT_FORWARD_ SHORT_MESSAGE (SMSC-GT-1) Page
Positive page response
CP_DATA CP_ACK CP_DATA CP_ACK MAP_MT_FORWARD_ SHORT_MESSAGE _ACK SC_RP_ACK
1. The subscriber has been absent (for example, the mobile was turned off), and the Mobile-Not-Reachable-Flag (MNRF ) has been set in the VLR and HLR. When the subscriber becomes available (for example, turns his or her mobile on), the VLR sees from the MNRF that there are messages waiting for the subscriber, and informs the HLR with ReadyForSM operation. Finally, the MNRF is cleared.
See MAP in SMS for a more detailed description of ReadyForSM operation.
After the HLR has been informed about the available subscriber, the Message-Waiting-Data of that subscriber is read and an alert is sent to every SMSC address found on the MWD list. Finally, the MNRF is cleared.
2. The memory capacity was exceeded (either the mobile station or the SIM card memory was full), and the Memory-Capacity-Exceeded-Flag was set in the HLR. When the MS informs the VLR that it has free memory again, the VLR sends the ReadyForSM operation to the HLR.
After the HLR has been informed about the available memory, the Message-Waiting-Data of that subscriber is read and an alert is sent to every SMSC address found on the MWD list. Finally, the MCEF is cleared. See the figure below:
Figure 10. SMSC alerting
The steps are the following:
SMSC HLR MSC/VLR SMS-IWMSC ReadyForSM AlertServiceCentre Alert 1 4 2 3
1. The MS informs the VLR that it has free memory or has become reachable again .
2. The VLR informs the HLR with ReadyForSM that the subscriber is available or that there is free memory.
3. The HLR searches all SMSC addresses listed in MWD from the subscriber data and sends an Alert-SC to each of them.
4. The SMS-IWMSC forwards the Alert-SC to the SMSC through OSI or TCP/IP application.
There are two types of repeated delivery attempts from the SMSC (the providers of the SMSC and the network define their application):
1. A repeated delivery attempt because the SMSC has been informed that the MS is active and available for receiving SMs.
2. An automatic repeated delivery attempt performed by the SMSC. During the Alert-SC procedure there is no load sharing. For further details, see SMS load sharing . You can also find a list of SMS information elements . For further details, see SMS load sharing . You can also find a list of SMS
information elements .