There can be many reasons why your Omni app may not be ringing, here are some common diagnoses: 


But before we look into the steps, do ensure that you are running on the latest Android OS and the latest Omni version!


Method 1: Disable Battery Optimization for Omni

After Android 6.0 Marshmallow, Google introduced features such as Doze Mode and App Standby to extend battery life of your phone.


While these help with battery life, it can also cause Omni to not work when in the background.


Battery optimization is hidden in different parts of the settings for different phones, here are some common ones where you can find them:


Steps:

1) Look for the “Settings” app

2) Find ‘Apps’ or ‘Apps & notifications’

Press the gear icon on the top-right corner of the screen and then press the “Battery optimization” > find ‘Omni’ and run ‘Not optimize’


OR


2) Under ‘Advanced’, find ‘Special app access’ or ‘App Info’ and select ‘Battery optimization’ > find ‘Omni’ and select ‘Not optimize’


OR


2) Find ‘Battery’ > ‘Battery optimization’ > find ‘Omni’ and run ‘Not optimize’


OR 


2) Find Device Care > Battery > Battery Usage (next to Estimated battery life).

From the 'Battery usage since last full charge' section, tap on one the options (Screen, Call standby, etc.).


Generally, once you are looking at your apps or battery optimization, you should Select “All apps” and look for ‘Omni’. Try to look for battery-related settings, select “Don’t optimize”.



More information can be found here: https://www.makeuseof.com/tag/androids-battery-optimization-harm-good/


Method 2: Avoid using task killer apps

Task killer apps are apps such as Clean Master, ES Task Manager, Advanced Task Manager, ShutApp and more. These apps function to force kill your apps that are running in the background.


While these apps can help you save battery life or free up RAM, it can mean bad news for your apps (and also may backfire and cause more battery to use to restart apps). 


Ensure that Omni is not affected by these apps or completely remove the apps to ensure all your apps function optimally.


Method 3: Permission Settings

Sometimes, it may just be that permissions were accidentally disabled during installation. 

Find “Omni” inside “Settings” > “Apps” > “Omni” > “Permissions” and make sure that all the permissions are allowed.