Sync iPad to iPhone for calling on both devices?
How do I sync iPad and iPhone without a computer?
iPhone 11, iOS 13
Sign-in to iCloud on both devices with the same AppleID - and enable the items that you wish to synchronise in your iCloud Settings:
Settings > [Your Name / AppleID] > iCloud - enable services as needed
If you are already signed-in on both iPad and iPhone with the same AppleID (and services are enabled), we’ll need more details of what isn’t working - and any symptoms or errors that you see.