Why SMS showing as delivered, but the user didn't receive it on their handset?

When an SMS shows Delivered, it means the message has been successfully handed over from the operator network to the recipient’s device. However, in many cases, the user may still report that they never saw the message.

Most such cases are caused by smart SMS filtering, spam detection, or device-level settings, not by delivery failure.

Below are the most common reasons and how to resolve them.

1. Smart Messaging Apps Automatically Categorize SMS

Modern Android devices use AI-driven filtering within messaging apps such as:

• Google Messages

• Samsung Messages

• Xiaomi / MIUI Messages

• Oppo / Realme Messages

• Vivo Messages

These apps classify messages into folders like:

• Promotions

• Offers

• Finance

• Spam / Junk

• OTP (for some devices)

As a result, messages may not appear in the primary inbox, even though they are delivered to the handset.

Common triggers for auto-categorization:

• Sender ID is used frequently for promotional messages

• Message content containing marketing-style text

• Repetitive templates or URLs

• Predictive spam/AI filtering by OEMs

2. Handset-Level Spam Filters May Hide SMS

Device manufacturers (Samsung, Oppo, Xiaomi, etc.) include spam-blocking algorithms that may hide or auto-route messages without notifying the user.

These filters analyze:

• Sender reputation

• Message volume

• Historical user interaction with similar messages

• Keyword patterns

Even with a successfully delivered DLR, the user may never see the SMS unless they check their spam folders.

3. Inbox or Cached Filter Issues

Messaging apps sometimes hide messages automatically when:

• There are too many messages from the same sender

• Earlier messages were deleted or marked as spam

• Cached filters continue applying older rules

This is especially common on devices with MIUI and ColorOS.

4. Device or SIM Issues

Less frequently, the issue may be caused by:

• Outdated messaging app

• SIM card not refreshed after device change

• Network caching

• DND restrictions

• Background app limitations

A successful DLR does not guarantee visibility in these cases.

How the User Can Resolve It

Please ask the recipient to try the following steps:

✔ 1. Check all message folders

• Spam / Junk

• Promotions

• Offers

• Finance

• Others (depending on handset model)

✔ 2. Delete older messages from the same sender ID

This helps reset the device’s filtering logic.

✔ 3. Restart the device or reinsert the SIM

Refreshing network registration often resolves indexing issues.

✔ 4. Update the messaging app

Make sure Google Messages or the manufacturer’s messaging app is updated to the latest version.

✔ 5. Disable smart filtering or spam protection (if available)

Many devices have options such as:

• “Disable SMS categorization”

• “Turn off Spam Protection”

• “Disable Smart Inbox”

✔ 6. Use different sender IDs for OTP and promotional SMS

This is considered an industry best practice.
Using one sender ID for OTPs and another for other types of communication improves sender reputation and reduces filtering.

✔ 7. Create multiple sender IDs (recommended)

Mapping multiple sender IDs to the same templates helps distribute traffic and reduces the chance of mass filtering.

Important Note

Handset-level filtering and smart categorization are controlled entirely by the device manufacturer and messaging app algorithms.
This process is not controlled by telecom operators or MSG91, which is why the message still shows Delivered even when not visible to the user.