Call Flow

The following figure illustrates an IDP message that is subject to IDP screening for prepaid.

Figure 5-8 IDP Message Subject to IDP Screening for Prepaid

1. HLR sends the MAP Insert_Subscriber_Data message to MSC to arm trigger points.

2. MSC formulates an INAP IDP message and sends it to vSTP with a Service Key encoded as follows:
   • ServiceKey = xx for voice and text calls originated from prepaid subscribers with "unlimited" call and text plan
   • ServiceKey = yy for text calls originated from prepaid subscribers with "unlimited" call and text plan
   • ServiceKey = zz for all other types of prepaid calls
   vSTP intercepts the INAP IDP message and determines the disposition of the call by examining the following values of the parameters encoded in the INAP IDP message:

   • ServiceKey
   • TeleService
   • CallingPartyNumber
   • CalledPartyBCDNumber
3. Based on the Service Key parameter values, the vSTP performs on of the following:
   1. The vSTP returns an INAP Continue Message to the MSC if any one of all the following 3 scenarios is identified:
      • Prepaid voice calls originated from prepaid subscribers with "unlimited" call and text that include:
        • ServiceKey = xx
        • TeleService = Telephony (value = 17)
        • Both Calling Party Number and CalledPartyBCDNumber are found in the In-Network Subscriber List
      • Prepaid text calls originated from prepaid subscribers with "unlimited" call and text that include:
        • ServiceKey = xx
        • TeleService = Short MessageMO-PP (value = 34)
        • Both Calling Party Number and CalledPartyBCDNumber are found in the In-Network Subscriber List
      • Prepaid text calls originated from prepaid subscribers with "unlimited" text that include:
        • ServiceKey = yy
        • TeleService = Short MessageMO-PP
        • Both Calling Party Number and CalledPartyBCDNumber are found in the In-Network Subscriber List
   2. For all other scenarios, the vSTP relays the INAP IDP message to its intended destination.