Open the Phone app
Tap the menu or settings icon
Select Call settings
Tap Call forwarding or Call diversion
Choose Always forward, Forward when busy, Forward when unanswered, or Forward when unreachable
Enter the phone number to divert calls to
Tap Turn on or Enable
Save the settings
To turn it off, return to Call forwarding and disable the option
If using a landline, contact your service provider for call diversion setup
If using iPhone, go to Settings, then Phone, then Call Forwarding
If using Android, the exact path may vary by device and carrier