Transferred Account Procedures (TAP) are essential mechanisms in GSM (Global System for Mobile Communications) networks, facilitating the billing process for roaming subscribers. When a mobile subscriber uses their phone in a network other than their home network, TAP procedures come into play to ensure accurate and efficient billing. Here’s a detailed explanation:
- Role in Roaming: In GSM roaming, a subscriber can use their mobile phone in a network that is different from their home network. This is known as visiting a foreign network or roaming. When roaming, the Visited Public Mobile Network (VPMN) provides network services to the subscriber.
- Billing Records Transfer: The core function of TAP is to transfer billing records from the visited network (VPMN) to the subscriber’s home network operator (HPMN). This transfer ensures that the home network can accurately bill the subscriber for the services used while roaming.
- Evolution of TAP Versions:
- TAP1: The initial version, providing basic functionality for billing record transfer.
- TAP2: An improved version with enhanced features and more detailed billing information.
- TAP2+: This version further refined the billing process, including more specific billing scenarios.
- TAP3: The latest and most advanced version, TAP3, supports a broader range of services and technologies. It includes support for inter-standard roaming, which means it can handle billing for roaming not only in traditional GSM networks but also in other networks like satellite, WLAN (Wireless Local Area Network), UMTS (Universal Mobile Telecommunications System), and other 3G technologies.
- Importance of TAP3: With the advent of various new technologies and the increasing complexity of mobile services, TAP3’s ability to handle diverse billing scenarios has become crucial. It ensures seamless and accurate billing for a wide range of services across different network standards.
- Interoperability and Standardization: TAP procedures are standardized to ensure interoperability between different mobile network operators worldwide. This standardization is crucial for enabling global roaming services, where subscribers can use their mobile phones in various networks around the world.
In summary, TAP is a set of procedures that play a critical role in the GSM mobile communication system, particularly in the context of roaming. Its evolution from TAP1 to TAP3 reflects the growing complexity and diversity of mobile services and the need for robust, adaptable billing mechanisms in the global telecommunications landscape