Use FaceTime with your iPhone and same Apple ID
On iPhone, go to Settings > Phone > Calls on Other Devices
Turn on Allow Calls on Other Devices
Turn on your iPad in the device list
On iPad, go to Settings > FaceTime
Sign in with the same Apple ID as your iPhone
Turn on FaceTime
Open FaceTime on iPad
Tap New FaceTime
Enter a contact name, phone number, or email
Tap the audio or video call button
Use Wi-Fi Calling through your iPhone if your carrier supports it
Use third-party calling apps like WhatsApp, Skype, Zoom, or Google Voice
Install the calling app on your iPad
Sign in to the same account
Grant microphone permissions when prompted
Start a call from the app’s contacts or dial pad
Use a Bluetooth headset or AirPods for better audio
Keep your iPhone nearby and connected for cellular call relay