> ## Documentation Index
> Fetch the complete documentation index at: https://moengage-analytics-query-api-docs.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-analytics-query-api-docs/d3J9GC--OlIl9xey/images/moengage_06d833.png?fit=max&auto=format&n=d3J9GC--OlIl9xey&q=85&s=899c50f5e990784d88243642f4021cad" 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-analytics-query-api-docs/eGXlUPWPPC19b0Gq/images/moengage_93aff4.png?fit=max&auto=format&n=eGXlUPWPPC19b0Gq&q=85&s=2d9c1a0f7f3cbb632021ec20802eadbd" 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.​​