If you have an iPhone and a Mac or iPad, you can link your phone number to your iCloud account to send and receive calls and messages of the same number on both devices.
Add new or existing number to iOS
You need to make sure your devices are connected to the same account iCloud account for everything to synchronize correctly.
The process is the same for all iOS devices, but you must first activate your existing number on your iPhone. On your phone, open the Settings application.
Tap on the category marked "Messages".
Make sure you are logged in and that iMessage is enabled. Scroll down and tap "Send and Receive."
There may be a prompt asking you to log in with your Apple ID for use with iMessage. If yes, log in.
Once logged in, make sure your phone number is checked under "You can receive and reply to iMessages". If so, it's good for iMessage.
FaceTime still needs to be configured. Return to the main Settings window and press the FaceTime settings.
Make sure you use your Apple ID for FaceTime and activate your number under "You can be contacted by FaceTime at".
Now that your iPhone shares its phone number, you can enable the same settings on your iPad or iPod Touch to sync messages between devices.
Add your phone number to macOS
Now that your phone is set up, you can switch to your Mac. Open messages and you will be asked to to log in if you have never used it before. Open the message preferences by pressing Command + Comma or by selecting "Preferences" from the "Messages" drop-down menu in the top menu bar.
If you set up your phone correctly, your phone number should appear under "You can be contacted to receive messages to". It will probably be enabled by default.
All iMessages sent to your phone number will be sent to your Mac. This does not cover text messages however; for that, you will have to activate text message transfer.
For FaceTime, the process is the same. Open the FaceTime settings and you will see the same window with a checkbox next to your phone number.
This will connect your phone and your Mac for FaceTime calls, but if you want to receive cellular calls on your Mac, you must enable phone call forwarding.
Delete a number
To delete a number, uncheck the box in the iMessage and FaceTime preferences of the device you want to delete. This will prevent you from receiving future calls and texts on this device.
If you want to completely remove it from your iCloud account, you must turn off your iPhone. If you do not own the phone (for example, if you sold it without having previously wiped it or it was stolen), you can change your password identification Apple to force the phone to disconnect. Although in the case of a stolen phone, you can still wipe it off with Find My iPhone, which will solve the problem during the process.