USSD Workflow & Benefits

Hi Friends, 

Here are some more details about USSD Workflow & Benefits,

Working Principle:- 

•          USSD Originated at Network Side 

1. USSD Originated by HLR – In HLR, application is there from where it originates a session with MSC/VLR, sends a USSD_REQUEST or USSD_NOTIFY messages to MSC/VLR & waits for the response. As the response received by MSC/VLR, HLR releases the session or sends another USSD_REQUEST or USSD_NOTIFY messages on the same session. After receiving the USSD messages from the HLR, if the MS is reachable, the MSC/VLR originates a session to the MS and transparently transmits the received USSD messages and the subsequent messages between the MS and HLR. If one of the sessions (the session between the HLR and MSC/VLR and that between the MSC/VLR and MS) is released, the MSC/VLR releases another session. 
2. USSD Originated by MSC/VLR - In MSC/VLR, application is there from where it originates USSD_REQUEST or USSD_NOTIFY messages, if the MS is reachable, the MSC/VLR originates a session to the MS, sends an USSD_REQUEST or USSD_NOTIFY message to the MS, and then waits for the response. MSC/VLR controls the session. After receiving the response from the MS, the MSC/VLR can release the session or sends another USSD_REQUEST or USSD_NOTIFY message on the same session. In certain cases, such as application timeout in the MSC/VLR, the MSC/VLR can release the session before receiving the response from the MS. 
3. USSD Originated by External Nodes - The external nodes, such as the USSD center and SCP (Service Control Point/IN), can originate USSD, Based on the routing mode of the short message center in sending short messages, the external node sends a message to the home HLR of the subscriber. If the MS is reachable, the HLR sends the address of the MSC/VLR that serves the MS to the external node. After obtaining the address, the external node directly sends an USSD_REQUEST or USSD_NOTIFY message to the MSC/VLR. The MSC/VLR then transparently transmits the message to the MS. The subsequent messages between the external node and the MS are also transparently transmitted by the MSC/VLR. 
4. Processing of MS for USSD Operation Originated by Network - The MS may receive, at any time, the USSD operation originated by the network. If the MS has an on-going USSD operation or a supplementary service that is unrelated with calls, the MS rejects the USSD operation originated by the network. If the MMI (Man-Machine Interface) does not meet the requirement of USSD, the MS also rejects the USSD operation originated by the network. If the MS does not support the characters of the USSD operation, the MS sends a message to inform the network. 

•            USSD Originated by MS (Mobile Station) 

1. Processing of MS – Before originating USSD, the MS sets up the CM connection with the network. After the CM connection is set up, the MS sends the USSD request to the MSC and waits for the response. After receiving the response from the network, the MS displays the received information for the subscriber. When the MS waits for the response, the MS may receive a USSD_REQUEST or USSD_NOTIFY message sent by the network. Upon receiving the message, the MS processes accordingly and then continues to wait for the response to the initial USSD request. 
2. Processing of MSC/VLR - After receiving the USSD message sent by the MS, the MSC/VLR processes the message based on the SC (Service Code) in the message. Depending on SC, MSC/VLR processes the USSD operation in the local office or with HLR, if the MSC/VLR does not support the characters in the USSD message or if the session cannot be set-up with HLR, the MSC/VLR returns an error to the MS. 
3. Processing of HLR - After receiving the USSD message, the HLR processes the message. If the HLR does not support the characters in the USSD message, the HLR informs the MS and releases the session. 

 

USSD Benefits:-

• For Carriers - Many Real-Time value-added services can be provided, such as those providing stock, lottery, weather forecast, and airline information. These services can attract subscribers.
• For Mobile Subscribers - Subscribers' requirements in many fields can be fulfilled, such as querying lottery information and stock information. 
• Applicable-to Network – It’s applicable to all the GSM/UMTS networks, There is no special requirement for software/hardware, but USSD center is required.

Flow details will be coming soooon...

Keep checking for new posts till then HaPPy Reading.

ChEEeeerS

Telecom Tigers Team

telecomtigers@gmail.com
http://homepageforu.webs.com/