“17  Absent Subscriber. IMSI detached.” —
is a GSM (Global System for Mobile Communications) MAP error code, specifically MAP error code 17.

Here’s what it means:

Meaning

• Code: 17

• Name: Absent Subscriber

• Description: The subscriber’s IMSI (International Mobile Subscriber Identity) is currently detached from the network.
  This means the subscriber’s device is not registered on the mobile network — for example, the phone is switched off, out of coverage, or has not yet re-attached after a restart.

When It Occurs

You typically see this error when:

• Attempting to deliver SMS to a subscriber who is not reachable.

• Trying to initiate a call or data session and the HLR/VLR reports the IMSI as detached.

• The subscriber’s location update failed or timed out in the network.

Typical Handling

• SMS-C (Short Message Service Center) will usually store the message and retry later when the subscriber re-attaches.

• Voice calls may receive a “Subscriber not available” or “Out of coverage” message.

• Network operators monitor such events via HLR/VLR logs or MAP trace to verify whether the IMSI re-attaches later.

✅ Summary