Oppo
Make a Phone Call auf Oppo
Placing a call on an Oppo phone works through the built-in Phone app, which handles both the dial pad and your saved contacts in one place. Confusion usually starts when a device has two SIM cards, since ColorOS then asks which SIM should place the call every time.
The dial pad is the fastest option if you already know the number by heart. The Contacts tab is better when you are calling someone saved on the device, since you avoid typing errors on longer numbers.
To place a call, tap Phone, then choose Contacts or Dial pad. Enter the phone number if you used the dial pad, then tap the Phone button to start the call.
On dual-SIM devices, ColorOS shows a prompt to choose a SIM card. Pick the SIM that matches the plan or number you want to call from.
If the call button stays grayed out or nothing happens after tapping it, check whether the correct SIM is inserted and active under network settings, since a disabled SIM slot will block outgoing calls even though the dial pad still works normally.