Since VoLTE works in the background, it can be hard to tell if it's actually active. The easiest way to verify it is to watch your phone's status bar while you are on a live call.
The "Live Call" Test
To see VoLTE in action, disable your Wi-Fi temporarily and make a phone call. Watch the signal icon at the top of your screen:
✅ You ARE using VoLTE: The network indicator stays on 4G, LTE, or 5G throughout the duration of the call.
❌ You are NOT using VoLTE: The indicator drops down to 3G, H, E, or G as soon as the call connects.
Visual Indicators by Device
On Android
Status Bar Icon: Many Android phones will display a small "VoLTE" or "HD" icon next to the signal bars.
In-Call Screen: Look for an "HD" badge or "High Definition" text next to the timer during your call.
On iPhone
Network Icon: iPhones do not typically show a "VoLTE" logo. Instead, simply ensure the "4G" or "5G" symbol does not disappear or change when you start speaking.
Data Speed: If you can still browse the web at high speed or use a map app effectively while talking, you are successfully using VoLTE.
What if it's not working?
If your phone consistently drops to 3G during calls, check these three things:
Settings: Ensure the "VoLTE" or "4G Calling" toggle is switched ON in your Cellular/Mobile Data settings.
Coverage: You must be in a 4G or 5G coverage area to use VoLTE.
Device Compatibility: Ensure your phone model is VoLTE-capable (most devices made after 2019 are) also ensure that the device is one which is supported by ONSIM, a full list can be found here.