In case of International Roaming, DTAC has CAMEL roaming agreements with some of the roaming partners and with some of the roaming partners; they don’t have CAMEL roaming agreements but had settlement agreements. Since the prepaid subscribers are always charged at the time of the event, so they need to have the CAMEL agreements with the roaming partners so that they can be charged in real time. In order to allow the Individual subscriber to use the roaming services in the countries where DTAC does not have the CAMEL agreements, DTAC can ask the subscriber to have a postpaid account and the subscriber roaming usage will be charged to the new postpaid account. The other charges will still go to the prepaid account.
Once the postpaid account has been created, a payment relationship can be created between the prepaid subscriber and the postpaid account. This has been explained in the figure below: