Oppo
Turn Call Waiting On or Off auf Oppo
Call waiting notifies you about a second incoming call while you are already on a line on your Oppo phone. Without it, the second caller either hears a busy tone or gets sent to voicemail, depending on your carrier.
The setting sits inside the network-related menus of ColorOS, not in the general Phone app settings. Carriers can pre-activate call waiting on the SIM level, but the toggle on the device only takes effect if the network supports it and the SIM status allows it.
Turn call waiting on or off here: Tap on Phone ➤ Open the Menu ➤ Tap on Settings ➤ Tap on Calling accounts ➤ Tap on Carrier call settings ➤ Tap on Additional settings ➤ Choose a SIM card (Dual SIM) ➤ Enable or disable Call waiting.
On dual SIM devices, this setting applies per SIM card, so check both slots if you use two numbers on the same phone. If the toggle stays greyed out, the carrier controls the setting on their end and it cannot be changed from the device.
Turning call waiting off makes sense if you rely on a separate voicemail service or want a second call to go straight there while you are busy. Turning it on helps if you regularly expect urgent second calls, for example during work hours.