> ## Documentation Index
> Fetch the complete documentation index at: https://moengage-add-partner-guide-reddit-ads-conversions.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Why Do Push Notification Tests Often Fail for Mobile Numbers?

> Resolve push notification test failures when using mobile numbers by switching to the unique user ID field to identify reachable users instead.

## Problem

When attempting to send a test push notification campaign, the notification fails, and the following message is displayed:

Installed User not found for Mobile Number = 0000000000

<img src="https://mintcdn.com/moengage-add-partner-guide-reddit-ads-conversions/IzwduNscJ6PV_FXj/images/moengage_06d833.png?fit=max&auto=format&n=IzwduNscJ6PV_FXj&q=85&s=c7de8b9d76756b0a47599a8f6bb2570d" width="556" height="304" data-path="images/moengage_06d833.png" />

## Solution

* Use the unique ID field of reachable user instead of the Mobile Number attribute to ensure push notifications are sent.
* The unique ID field can be found in the user profile with the name **ID**.
  <img src="https://mintcdn.com/moengage-add-partner-guide-reddit-ads-conversions/nkT_HxDV9WG1qiJY/images/moengage_93aff4.png?fit=max&auto=format&n=nkT_HxDV9WG1qiJY&q=85&s=f0406010fd1dfee9ee3603ce9f5cd08b" width="1600" height="275" data-path="images/moengage_93aff4.png" />
* The unique ID is unique to each user and is used to determine whether the user can receive push notifications.​​