So if you are receiving the calls, but it's not ringing when your phone is in sleep mode, then you are not receiving PUSH notifications. There are several checks you can do to try and fix this

It's obvious, but check first that the 3CX App has network connectivity. You can switch off mobile data for some apps, obviously it needs to be on for 3CX to work.

Check 1: Are you using the right phone, latest Android and 3CX?

To have good results, you will need to use a quality phone with a recent version of Android:

• Android 10+ - Check that you have Android 10 or above. Should really be at least Android 11.
• Recent quality phone - Ensure you have a quality phone from Google, Samsung, Oppo, Motorola, Oneplus for example. No-name China phones can cause problems. It’s not just the hardware, it's also the version of Android that gets installed on it and the agreements (or lack of agreements) they might have with Google with regard to Play Store and Push.
• 3CX V18 - Upgrade to v18 to get significant improvements in terms of using mobile phones with 3CX.

Please note, we will only support the latest versions of phones, Android and 3CX. We allow installation of the app on Android 8 or 9, but we will not support or troubleshoot.

Check 2: Switch off battery optimisation (REQUIRED for Android 14 & 15)

Some versions of Android have battery optimisation settings turned on that terminate background apps, including 3CX, of course. We need to switch that off:

1. Launch “3CX”.
2. Tap on the top left hamburger menu.
3. Tap on “Settings > Advanced”.
4. Enable “Switch Off Battery Usage Optimisation”.
5. Select All Apps > 3CX
6. Make sure ‘Allow background usage’ is turned on
7. Tap on ‘Allow background usage’ text
8. Select “Don’t Optimise / Unrestricted”. (Name differs on Android versions and Phones)

Please note for Oppo you should follow the steps below:

1. Look for the Settings App.
2. Tap on “App management”.
3. Tap on “App list”.
4. Find “3CX”.
5. Tap on “Battery Usage”.
6. Enable “Allow background activity”. 

Check 3: Switch on Background Data for the 3CX App

Enabling background data is required to push through notifications even when the app is not in use. To switch it on:

1. Launch “3CX”.
2. Tap on the top left hamburger menu.
3. Tap on “Settings > Advanced”.
4. Enable “Switch On Background Data”.
5. Select “Unrestricted data usage” and “Background data”.

Check 4: Using Android 13 or 14? Give the App full permissions

1. Open Android settings and tap on “Apps”.
2. Search for the 3CX app and tap on it.
3. Tap on “Permissions”.
4. Tap on “Notifications” under the 'Not allowed' section.
5. Turn on the switch for “All 3CX notifications”.

Check 5: Is ‘Do Not Disturb’ enabled?

Enabling ‘Do Not Disturb’ will prevent the receipt of PUSH notifications. There are 2 ways to enable DND, from inside the app, and via the Android OS settings.

In-App DND

When opening the 3CX App, you will see a status icon at the top right corner in the header which shows your current status. If this is set to red, you are currently in DND mode. Change your status to ‘Available’ to receive notifications, simply by clicking on the Status icon and selecting the desired status.

Android OS DND

Android OS offers the ability to limit interruptions and silence your phone by setting it to ‘Do Not Disturb’. To turn off ‘Do Not Disturb’:

1. Swipe down from the top of your screen to show the Notifications panel.
2. Tap on ‘Do Not Disturb’ and set to ‘Off’.

Should this have been done intentionally, Android allows you to set which apps can ignore this rule.

Please follow this guide by Google which explains the steps needed in further detail.

Check 6: Pre-installed or third party cleaner apps

Certain apps may be installed on your phone either by the manufacturer or by you, which could be closing the 3CX app in the background to enhance your phone's speed. These apps are typically maintenance, cleaner or optimiser apps.

To avoid missing out on PUSH notifications, it is important to identify these apps and either disable, uninstall or whitelist the 3CX app client.

Examples of such apps:

• MIUI Optimisation by Xiaomi
• System Maintenance by Blackview
• Droid Optimiser
• Greenify

Check 7: Got a firewall in front of 3CX? Open the ports!

If you have installed 3CX on premise, or are self-hosting 3CX behind a firewall that you manage, it can very well be that your firewall is blocking communication to the Google Firebase Cloud Messaging (FCM) service. See this document to learn about the ports you have to open.

Check 8: Grant Permission for Full Screen Notifications

Google states that users who upgrade from previous Android versions to Android 14 should have this permission enabled by default. If you experience the above problem after upgrading to Android 14, you need to enable this permission manually. To enable:

1. Open the 3CX app
2. Tap on the hamburger menu (top left icon of the app)
3. Tap on “Settings” > “Advanced”
4. Scroll down to “Notifications, audio & visual effects”
5. Tap on the toggle next to ‘Answer on lock screen’
6. A new window will appear. Tap on the toggle bar to allow “Full screen alerts”

Note: Certain MIUI devices running on older Android versions also require this permission to be enabled.

If all else fails - Enable “Keep Active” feature

If for some reason you cannot get Push to work, because you cannot change your phone or manage the network you are on, then you can temporarily enable the “Keep Active” function. This will keep a permanent connection open to your 3CX server. Battery usage will be significantly  increased.

Send us technical feedback

You can provide us with your technical feedback by sending us a verbose log from the app while the issue occurs so we can investigate further:

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1. Open “3CX”.
2. Enable Verbose Logs: “Android App Settings (top left hamburger menu) > Settings > Advanced > Troubleshooting > Verbose Logging”.
3. Reproduce issue and “Generate Log Report”: Android App Settings (top left hamburger menu) > Settings > Advanced > Troubleshooting > Send Log Report.
4. Send this log report via email to your PBX administrator so he can communicate with us via 3CX Support and/or Forum.