> ## Documentation Index
> Fetch the complete documentation index at: https://moengage.com/docs/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/CaPmX0z_ys8cr0ms/images/moengage_06d833.png?fit=max&auto=format&n=CaPmX0z_ys8cr0ms&q=85&s=b6416f67d730ca20bbc40af8bfe96ba4" 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/E3HJVtaUzhrzFckK/images/moengage_93aff4.png?fit=max&auto=format&n=E3HJVtaUzhrzFckK&q=85&s=51e1bdf355f6a20dabc75b02b4f4f54f" 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.​​