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Mobile Prepaid Phone Service 2003. 5. 13. Kim Myung Jo (silveraspen@hanmail)

Mobile Prepaid Phone Service 2003. 5. 13. Kim Myung Jo (silveraspen@hanmail.net) Communication Protocol Engineering Lab. Contents. Mobile Prepaid Services Wireless Intelligent Network Approach Service Node Approach Hot Billing Approach Handset-Based Approach

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Mobile Prepaid Phone Service 2003. 5. 13. Kim Myung Jo (silveraspen@hanmail)

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  1. Mobile Prepaid Phone Service 2003. 5. 13. Kim Myung Jo (silveraspen@hanmail.net) Communication Protocol Engineering Lab. Myung Jo. Kim.

  2. Contents • Mobile Prepaid Services • Wireless Intelligent Network Approach • Service Node Approach • Hot Billing Approach • Handset-Based Approach • Comparison of the Prepaid Solution Myung Jo. Kim.

  3. Overview • Traditionally prepaid phone • A telecommunication service that requires a customer to pay before making calls • Public phone (use coin) • Public phone (use prepaid card) • Prepaid telecommunication services • Offered in Europe and Asia in 1982 • Became popular in the United States in 1992 • More than 30 prepaid solution vendors are currently competing for carrier business • Mobile prepaid service • Has been growing exponentially all over the world Myung Jo. Kim.

  4. Advantage and Characteristic • Service provider • Reduce the business operation costs • Customer • Provide immediate service without the need for long-term contracts • Many end users just want to enjoy the service • Do not want to fill in subscription forms • Difference of two type of prepaid service (fixed vs mobile) • A fixed telephone service provider knows nothing about the prepaid customers • Fixed prepaid service allows outgoing calls only, whereas mobile prepaid service allows both incoming and outgoing calls Myung Jo. Kim.

  5. Mobile Prepaid Services (1/2) • In GSM prepaid service • A customer subscribes with prepaid credit • Coded into the subscriber identity module (SIM) card or kept in the network • Initialization of a prepaid customer must be completed within a certain number of days after subscription • If the balance is depleted • The customer cannot originate calls • Allowed to receive phone calls for a predetermined period • To recover the prepaid service • The balance has to be recharged by purchasing a top-up card , which is similar to a lottery scratch card • The system verifies and refreshes the account if it is a valid code Myung Jo. Kim.

  6. Mobile Prepaid Services (2/2) • Mechanism in the mobile prepaid service • An extra billing system for mobile prepaid service is required • A real-time usage metering function must be built in the prepaid service system to monitor the amount of remaining credit on the customer account • Sales taxed are generally collected at the point of sale (POS) for prepaid service • A customer care mechanism maintains items including customer activation and deactivation times, credit value, remaining time period, PIN Myung Jo. Kim.

  7. Wireless Intelligent Network Approach • WIN (Wireless Intelligent Network Approach) • A complete solution to prepaid service • A P-SCP (Prepaid Service Control Point) communicates with the MSC through SS7 signaling network • Several WIN triggers are defined • All billing information for a prepaid customer is stored in the P-SCP Myung Jo. Kim.

  8. WIN Call Origination Myung Jo. Kim.

  9. WIN Call Termination (called-party-pays billing) Myung Jo. Kim.

  10. WIN Prepaid Recharging Myung Jo. Kim.

  11. Service Node Approach (1/3) • The service node approach • The most widely deployed prepaid service solution at the initial stage of prepaid service provisioning • To deploy the prepaid service without interrupting the existing call models • Most mobile service providers implement service nodes in their networks to externally control prepaid billing • The service node is implemented using CTI (Computer Telephony Integration) techniques and PC-controlled PBX (Private Branch Exchange) • The same platform can be used to implement the prepaid service node effectively Myung Jo. Kim.

  12. Service Node Approach (2/3) • CTI • Utilize computer intelligence to manage telephone calls • APIs (Application Programming Interfaces) • TAPI (Telephony Applications Programming Interface) • TSAPI (Telephone Services Application Programming Interface) • Support general APIs that allows fast deployment • PC-controlled PBX • The software (C++) in the call control layer can be modified to implement various telecommunication applications • Provide larger and more cost-effective solutions than CTI switching Myung Jo. Kim.

  13. Service Node Approach (3/3) Myung Jo. Kim.

  14. Hot Billing Approach (1/2) • Hot billing • Uses CDRs (Call Detail Records) to process prepaid usage • The prepaid CDR is created in the MSC • The information in a CDR • Type of service • Date/ time of usage • User identification • The destination of the call • Location information • These records are generated when the calls are completed, and are transported from the MSC to the prepaid service center • The balance of the customer’s account is decremented according to the CDRs Myung Jo. Kim.

  15. Hot Billing Approach (2/2) • When customer uses up the prepaid credit • The HLR and the AuC are notified to prevent further service access • The prepaid service center instructs the network to route the next prepaid call attempt to an IVR • To play an announcement indicating that the balance has been depleted • The IVR can communicate with the customer to replenish the prepaid credit by using a top-up card, a credit/ debit card, or a credit transfer from a bank account Myung Jo. Kim.

  16. Hot Billing Architecture and Interfaces Myung Jo. Kim.

  17. Hot Billing Prepaid Service Initialization • Step1 • The customer subscribes to the prepaid service center at the POS or by calling the customer care center • Step 2 • The prepaid service center creates a subscriber data record including IMSI, MSISDN, account of credit, period of validity tariff model, and other authentication-related information • Step 3 • The prepaid service center activates the prepaid service by sending the customer data to the HLR, which then creates a record for the customer Myung Jo. Kim.

  18. Hot Billing Prepaid Call Origination Myung Jo. Kim.

  19. Hot Billing Customer Query and Recharging Myung Jo. Kim.

  20. Handset-Based Approach (1/3) • In the handset-based approach • The MS performs credit deduction during the call and determines when the credit limit is reached • The prepaid credit is stored in the MS • In the United States => special phones are required • For GSM => the credit is stored in the SIM card Myung Jo. Kim.

  21. Handset-Based Approach (2/3) • SIM card issues • Two partitions of SIM memory • Dialing numbers, short messages received, a menu of subscribed services • Programs that can be executed to carry out simple commands • AoC (Advice of Charge) message • To transfer the prepaid balance information and the tariff schemes • Provide information for the MS to produce a cost estimate of the services used • AoCC (Advice of Charge Charging) • AoCI (Advice of Charge Information) • To utilize handset-based prepaid service • The MS must support AoCC • AoCC is activated for every prepaid customer in an HLR which will be used in call setup and tariff switching Myung Jo. Kim.

  22. Handset-Based Approach (3/3) • Data fields in a SIM card • ACM (Accumulated Call Meter) • Accumulates the used prepaid units • ACM* (Accumulated Call Meter Maximum) • Records the amount of purchased prepaid credit • PUCT (Price per Unit and Currency Table) • The value of the home unit in a currency chosen by the subscriber Myung Jo. Kim.

  23. Handset-Based Prepaid Call Origination Myung Jo. Kim.

  24. Combined Prepaid Call Origination Myung Jo. Kim.

  25. Handset-Based Prepaid Recharging Myung Jo. Kim.

  26. Roaming • Roaming to other network • To provide roaming to prepaid customers • An agreement must be made between the home system and the visit system • This agreement is required so that the visited system can distinguish prepaid calls from the postpaid calls generated by roamers • Use special MSISDN • Prepaid charging • Cannot be performed at the visited system because the home system and the visited system may exercise incompatible prepaid service solutions • Most networks • Require the visited MSC to route the prepaid call back to the home network Myung Jo. Kim.

  27. Roaming to Other Networks for Prepaid Service Myung Jo. Kim.

  28. Scalability • The handset-based & the WIN approaches • have good scalability • The hot billing approach • The size of prepaid customer population is limited to the MSC’s capability to process and deliver CDR messages • The service node approach • The capacity of the trunks between the service node and the MSC limits the prepaid customer population that can be accommodated in the system Myung Jo. Kim.

  29. Fraud risk • The handset-based • AoC communication is not encrypted • It is possible to modify the credit illegally in the MS • Poor fraud protection • The hot billing approach • The risk of fraud can be high • Due to one-call exposure • The service node approach & the WIN approaches • Exhibit low fraud risk Myung Jo. Kim.

  30. Initial system setup • The handset-based • Dose not require changes to the mobile network infrastructure, except that the MSC must support AoC • Special SIM software is required to execute rate plans in the MS => Average setup cost and time • The hot billing approach • Requires the integration of the prepaid service center, the IVR recharging mechanism, and the MSC/HLR => Average setup cost and time • The service node approach • The mobile network not modified => Setup time is short and the setup cost is for the establishment of the service node • The WIN approaches • The design of services and switch software development for intelligent network is complex => Setup time is long and setup cost is very high Myung Jo. Kim.

  31. Service Features • Handset-based approach • Supports limited service features • the number of rate plans that can be stored in the SIM card is limited and cannot be conveniently updated • Hot billing approach • Better than average • The service node & the WIN approaches • Support flexible service features • None of the four approaches can support prepaid short message service • Because the short message is delivered by the SS7 TCAP, which cannot be identified by the MSC • Instead, charging for the short message is done at the SM-SC Myung Jo. Kim.

  32. Prepaid Short Message Service Myung Jo. Kim.

  33. Real-Time Rating • The handset-based approach • Real-time rating is performed at the MS • The service node approach • Real-time rating is performed at the service node • The WIN approaches • Real-time rating is performed at the P-SCP • The hot billing approach • Cannot support real-time rating • The credit information update depends on the MSC capability of sending CDRs Myung Jo. Kim.

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