ATI - Any Time Interrogation

Anythime Interrogation (ATI) is a procedure in the SS7 Mobile Application Part (MAP) protocol that allows a network entity to request information about a subscriber from the Home Location Register (HLR) or Home Subscriber Server (HSS) at any time.

This information can include subscriber location or other live data and plays a crucial role in delivering services like location-based services, fraud detection, and lawful interception.

The ATI operation is initiated by sending an ATI Invoke message to the HLR/HSS, which then processes the request and returns the desired subscriber information.

Process of Any Time Interrogation

1. Request Initiation: A network entity such as a Mobile Switching Center (MSC) or a Service Control Point (SCP) initiates an ATI request to the HLR/HSS.

2. ATI Invoke Message: This request is sent as an ATI Invoke message containing subscriber identifiers, which can include IMSI or MSISDN.

3. Processing by HLR/HSS: On receiving the ATI Invoke message, the HLR/HSS processes it to retrieve the requested subscriber information.

4. Response: The HLR/HSS sends a response back to the requesting network entity with the requested data.

Use Cases

• Location-Based Services (LBS): Provides real-time location information, enabling services like navigation, tracking, and location-based advertising.

• Fraud Detection: Monitors location and usage patterns to identify and prevent fraudulent activities, ensuring secure subscriber transactions.

• Lawful Interception: Assists law enforcement agencies by providing information necessary for legal surveillance and data collection.

Security Considerations

Ensuring that ATI requests are only executed by authorized entities is critical to protect subscriber privacy and data integrity.

Authentication and encryption mechanisms should be implemented to safeguard sensitive information throughout the process.

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ATSI Request

AnyTimeSubscriptionInterrogationArg ::= SEQUENCE {  
subscriberIdentity [0] SubscriberIdentity,  
requestedSubscriptionInfo [1] RequestedSubscriptionInfo,  
gsmSCF-Address [2] ISDN-AddressString,  
extensionContainer [3] ExtensionContainer OPTIONAL,  
longFTN-Supported [4] NULL OPTIONAL,  
...}