T4 AVPs
T4 (application id: 16777311)
The T4 interface is a crucial component within the Diameter protocol, specifically designed for communication between the Machine Type Communication Interworking Function (MTC-IWF) and the Short Message Service Service Center (SMS-SC) within a Home Public Land Mobile Network (HPLMN). T4 interface is instrumental in managing device triggers in IoT (Internet of Things) environments.
The primary purpose of the T4 interface is to facilitate the transfer of device trigger messages from the MTC-IWF to the SMS-SC. This interface ensures that critical information, such as the identities of serving network elements (e.g., SGSN, MME, MSC, SMSF), is conveyed accurately to the SMS-SC. The SMS-SC then processes these triggers and attempts to deliver them to the intended user equipment (UE). Additionally, the T4 interface allows the SMS-SC to report back to the MTC-IWF on the success or failure of the trigger delivery.
T4 interface workflow:
- Trigger Generation: The process begins with the MTC-IWF generating a device trigger. This trigger could be used to wake up a device, initiate a data session, or perform a specific action on the device.
- Message Transmission: The MTC-IWF sends the device trigger message to the SMS-SC via the T4 interface. The message includes important identifiers such as the serving SGSN, MME, MSC, or SMSF, depending on the context of the communication.
- Processing by SMS-SC: Upon receiving the trigger, the SMS-SC processes the message and routes it to the appropriate UE. This may involve interacting with other network elements to ensure the correct delivery path.
- Outcome Reporting: Once the SMS-SC has attempted to deliver the trigger, it reports the outcome (success or failure) back to the MTC-IWF. This feedback is crucial for the MTC-IWF to determine any further actions, such as retrying the trigger or logging the outcome for future reference.
For complete technical specification of T4 interface in Diameter protocol please refer to: [3GPP TS 29.337]
package com.mobius.software.telco.protocols.diameter.primitives.t4;
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Name |
AVP Code |
Data Type |
Vendor |
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Absent-Subscriber-Diagnostic-T4 |
3201 |
Enumerated |
3GPP |
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Indicates the reason why a subscriber is absent when a device trigger fails to be delivered due to the subscriber being unavailable. Enumerated Values: 0: NO_PAGING_RESPONSE: The subscriber did not respond to paging attempts from the network. This occurs when the UE is not reachable via any serving node. 1: UE_DETACHED: The User Equipment (UE) is detached from all serving nodes. The UE is either turned off or in an inactive state with no active network attachment. 2: UE_DEREGISTERED: The UE is deregistered in the network. The subscriber's registration status has been removed from the serving nodes. 3: UE_PURGED: The UE has been purged by one or more serving nodes. Purging can occur due to inactivity, network congestion, or explicit operator-triggered actions. 4: ROAMING_RESTRICTION: The UE is restricted from roaming in the current network. This could be due to subscriber policy, contractual restrictions, or regulatory limitations. 5: UNIDENTIFIED_SUBSCRIBER: The subscriber is not recognized in any serving node. This may occur due to incorrect subscriber information, missing profile data, or database inconsistencies. |
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Additional-Serving-Node |
2406 |
Grouped |
3GPP |
|
Contains the name, number, and realm of an additional serving node to be used for T4-triggering in Short Message Service (SMS) delivery scenarios. This AVP is primarily used in the T4 interface as defined in 3GPP [TS 29.173], facilitating SMS routing and delivery for both 3GPP and non-3GPP networks. The AVP structure is defined as follows: SMSF-3GPP-Name (Optional): The name of the 3GPP Short Message Service Function (SMSF) serving the subscriber. SMSF-3GPP-Realm (Optional): The Diameter realm of the 3GPP SMSF. SMSF-3GPP-Number (Optional): The number of the 3GPP SMSF responsible for handling SMS traffic. SMSF-Non-3GPP-Name (Optional): The name of the Non-3GPP SMSF responsible for SMS routing. SMSF-Non-3GPP-Realm (Optional): The Diameter realm of the Non-3GPP SMSF. SMSF-Non-3GPP-Number (Optional): The number of the Non-3GPP SMSF responsible for SMS delivery. SGSN-Name (Optional): The name of the Serving GPRS Support Node (SGSN). SGSN-Realm (Optional): The Diameter realm of the SGSN. SGSN-Number (Optional): The number of the SGSN used for SMS delivery. MME-Name (Optional): The name of the Mobility Management Entity (MME) responsible for MT-SMS processing. MME-Realm (Optional): The Diameter realm of the MME. MME-Number-for-MT-SMS (Optional): The number of the MME used for Mobile-Terminated SMS. MSC-Number (Optional): The Mobile Switching Center (MSC) number used for SMS routing. The following combinations are allowed: a) SGSN-Number b) SGSN-Name & SGSN-Realm & SGSN-Number c) MME-Name & MME-Realm & MME-Number-for-MT-SMS d) MSC-Number e) MSC-Number & MME-Name & MME-Realm f) SMSF-3GPP-Number g) SMSF-3GPP-Name & SMSF-3GPP-Realm & SMSF-3GPP-Number h) SMSF-Non-3GPP-Number i) SMSF-Non-3GPP-Name & SMSF-Non-3GPP-Realm & SMSF-Non-3GPP-Number |
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MTC-Error-Diagnostic |
3203 |
Enumerated |
3GPP |
|
Used in Mobile-Terminated Call (MTC) scenarios to indicate the cause of an error when attempting to replace an SMS message in the Short Message Service - Service Center (SMS-SC). Enumerated Values: 0: ORIGINAL_MESSAGE_NOT_DELETED: This cause is sent when the replacement attempt failed because the original SMS is still pending in the SMS-SC and could not be deleted. 1: NEW_MESSAGE_NOT_STORED: This cause is sent when the replacement attempt failed because the new SMS message could not be stored in the SMS-SC, possibly due to lack of storage resources or other constraints. |
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Serving-Node |
2401 |
Grouped |
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Contains the name, number, and realm of the serving node responsible for T4-triggering in Short Message Service (SMS) delivery scenarios. It is used in the T4 interface, as defined in 3GPP [TS 29.173], to provide details about the serving node currently handling the subscriber. The AVP structure is defined as follows: SMSF-3GPP-Name (Optional): The name of the 3GPP Short Message Service Function (SMSF) serving the subscriber. SMSF-3GPP-Realm (Optional): The Diameter realm of the 3GPP SMSF. SMSF-3GPP-Number (Optional): The number of the 3GPP SMSF responsible for handling SMS traffic. SMSF-Non-3GPP-Name (Optional): The name of the Non-3GPP SMSF responsible for SMS routing. SMSF-Non-3GPP-Realm (Optional): The Diameter realm of the Non-3GPP SMSF. SMSF-Non-3GPP-Number (Optional): The number of the Non-3GPP SMSF responsible for SMS delivery. SGSN-Name (Optional): The name of the Serving GPRS Support Node (SGSN). SGSN-Realm (Optional): The Diameter realm of the SGSN. SGSN-Number (Optional): The number of the SGSN used for SMS delivery. MME-Name (Optional): The name of the Mobility Management Entity (MME) responsible for MT-SMS processing. MME-Realm (Optional): The Diameter realm of the MME. MME-Number-for-MT-SMS (Optional): The number of the MME used for Mobile-Terminated SMS. MSC-Number (Optional): The Mobile Switching Center (MSC) number used for SMS routing. IP-SM-GW-Number (Optional): The IP Short Message Gateway (IP-SM-GW) number, used for routing SMS messages over IP-based networks. IP-SM-GW-Name (Optional): The name of the IP-SM-GW responsible for SMS delivery. IP-SM-GW-Realm (Optional): The Diameter realm of the IP-SM-GW. The following combinations are allowed: a) SGSN-Number b) SGSN-Name & SGSN-Realm & SGSN-Number c) MME-Name & MME-Realm & MME-Number-for-MT-SMS d) MSC-Number e) MSC-Number & MME-Name & MME-Realm f) IP-SM-GW-Number g) IP-SM-GW-Number & IP-SM-GW-Name & IP-SM-GW-Realm h) SMSF-3GPP-Number i) SMSF-3GPP-Name & SMSF-3GPP-Realm & SMSF-3GPP-Number j) SMSF-Non-3GPP-Number k) SMSF-Non-3GPP-Name & SMSF-Non-3GPP-Realm & SMSF-Non-3GPP-Number |
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SM-Delivery-Outcome-T4 |
3200 |
Enumerated |
3GPP |
|
Indicates the outcome of a device trigger delivery attempt in Short Message Service (SMS) over the T4 interface. Enumerated Values: 0: ABSENT_SUBSCRIBER: Indicates that the device trigger delivery failed due to the subscriber being absent from the network. The UE is unreachable, possibly turned off, out of coverage, or detached from the network. 1: UE_MEMORY_CAPACITY_EXCEEDED: Indicates that the device trigger delivery failed because the UE’s memory capacity has been exceeded. The UE cannot store additional SMS messages until space is freed. 2: SUCCESSFUL_TRANSFER: Indicates that the device trigger was successfully delivered to the UE. The MT-SMS message was successfully transferred through the serving node to the subscriber. 3: VALIDITY_TIME_EXPIRED: Indicates that the SMS message was deleted in the SMS Service Center (SMS-SC) due to expiration of its validity period. The message was not delivered before its predefined expiration time, leading to automatic removal from the SMS-SC. |
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Trigger-Action |
3202 |
Enumerated |
3GPP |
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Specifies the type of action to be performed on a device trigger in Short Message Service (SMS) over the T4 interface. It is used to indicate whether a new device trigger should be stored and sent, an existing trigger should be removed, or an existing trigger should be replaced. Enumerated Values: 0: TRIGGER: Requests the storage and sending of a new device trigger. This action is used when initiating a new device trigger request. 1: RECALL: Requests the removal of a pending device trigger. This action is used when a previously sent device trigger is no longer needed and should be deleted from the system. 2: REPLACE: Requests the replacement of a pending device trigger. This action is used when an existing device trigger should be updated with new information before being sent. |
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