Oppo
Turn VoLTE Calls On or Off auf Oppo
VoLTE (Voice over LTE) routes your calls through the 4G data network instead of the older 2G or 3G voice channel. Without it, your Oppo phone falls back to the slower network whenever it places or receives a call, which explains longer connection times and lower audio quality.
The setting lives in the mobile data menu, separate for each SIM slot on dual-SIM devices. If VoLTE does not appear as an option, either your carrier has not activated the feature on your account or your current plan does not include it.
How to switch VoLTE on or off
Go to Tap on Settings ➔ Tap on SIM card & mobile data ➔ Choose a SIM card (Dual SIM) ➔ Enable or disable VoLTE Calls.
Turn the toggle on to make calls over 4G, or off to fall back to the standard voice network. On dual-SIM phones, repeat the steps for the second SIM if it also supports VoLTE.
Disable VoLTE only if you are troubleshooting a specific reception issue or your carrier explicitly recommends it. In most areas, keeping it on gives faster call setup and reduces battery drain during calls compared to legacy voice networks.