Dialler rings people through your own mobile, so calls use the plan you already pay for and show your real number. When you click Dial on your computer, the call goes out through your phone over Bluetooth and you talk through your computer or headset. This takes about 10 minutes, once.
Which setup do you have?
Uses Phone Link, which comes free with Windows 10 and 11. Works with Android phones and iPhones.
Uses Apple's built-in call handover. Both devices must be signed in to the same Apple Account.
No setup needed. Open the app on your phone and Dial rings straight from it. This is also the way to go on a Chromebook, a Linux computer, or a Mac with an Android phone, because those can't hand calls to your mobile.