It is possible to back up phone contacts on an iPhone by using iTunes or by using iCloud. To back up using iTunes, install iTunes software on a computer and connect the iPhone via a USB cable. To back up using iCloud, only an Internet connection is required.
To use iTunes to back up phone contacts on an iPhone, first ensure the latest version of the software is installed from the official Apple website. Once the software is installed, connect the iPhone to the computer with a USB cable and select the device when it appears in the iTunes window. Once the iPhone has been selected, click on the Info tab and tick the box marked Sync Contacts. Once this has been done, click on the Backups tab and select Back Up Now. The contacts on the iPhone are backed up as a file on iTunes.
To use iCloud to back up phone contacts, navigate to the iCloud option under Settings and enter your Apple ID and password if requested. Tap Allow iCloud to activate the account and storage space. Once iCloud is activated, slide the Contacts button to the on position and select Back Up Now. For automatic backups, slide the iCloud Backup button to the on position.