Hi and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
It is not possible to delete the phone app. You problem deleted the shortcut from the home screen. Are you sure you don't see it on the menu/apps list screen ?
Go to Settings > Apps or Applications or Application Manager. Swipe left or right to All tab (next to downloaded, installed etc tabs) and do you see the Phone app there ? If so, select it and select Enable. If you see Disable there, tap it and tap Enable.
If that didn't work, then go to settings> Apps or Applications Manager > Disabled tab. Do you see phone app there ? If so, enable it.
If it still not working, then follow the steps belowl