therikb31 created an issue (kamailio/kamailio#4296)
For network-initiated UE de-registration, `ims_registrar_scscf` is populating the `Subscription-State` header of the `NOTIFY` message as `active;expires=3581` instead of `terminated`.
### Description
We are simulating a network-initiated UE de-registration by sending a **Registration-Termination Request** from the HSS to the S-CSCF for a registered IMSI.
**Call Flow**:
1. UE registers to the IMS core 2. S-CSCF performs third-party registration with the Application Server on behalf of the UE 3. Application Server subscribes to `Event: reg` for the registered IMSI 4. HSS sends a Registration-Termination Request for network-initiated UE de-registration 5. S-CSCF sends a `NOTIFY` to subscribers for the `IMS_REGISTRAR_CONTACT_DEREGISTERED` event (issue with the `NOTIFY` SIP message)
**Observation**:
1. `NOTIFY` messages are initiated to subscribers of `Event: reg`, but instead of having the `Subscription-State` header set to **terminated**, we observe the value **active;expires=3581**. (Image for the `NOTIFY` SIP message packet is attached below)
### Troubleshooting
#### Reproduction
To reproduce this, we are performing the following steps:
1. Performing SIP registration of the UE with the target S-CSCF node 2. Sending `SUBSCRIBE` requests from a third-party Application Server and the UE with `Event: reg` to get notified of registration events 3. HSS sends a `Registration-Termination Request` to the target S-CSCF for the registered IMSI (network-initiated de-registration)
#### Debugging Data
#### Log Messages
While going through the logs, we find that this header is being populated based on the expiry timer and a comparison with the current timestamp:
``` 2025-06-20 12:45:20 | 19(56) DEBUG: ims_registrar_scscf [registrar_notify.c:1716]: create_notifications(): Expires is greater than current time! Subscription state: [active;expires=3581] ```
#### SIP Traffic
### Possible Solutions
**Workaround**:
In the `create_notifications()` method of `src/modules/ims_registrar_scscf/registrar_notify.c`, when populating the `Subscription-State` header, if the `event_type` is `10` (`IMS_REGISTRAR_CONTACT_DEREGISTERED`), we can populate `Subscription-State` as `terminated`.
### Additional Information
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