Like other smart phones, the iPhone is capable of syncing data with e-mail applications including Microsoft Outlook. The synchronisation process is automatic and usually completes without any problems. But sometimes iPhone contact files do not sync properly and only half of your smart phone's names, addresses and other contact information is sent to Outlook. The missing contact information is left on your iPhone or within Outlook if the data was not originally in your iPhone. The problem is a software issue solvable through a number of ways.
Close any open programs and files. Open iTunes by clicking "Start," "All Programs" and the "iTunes" folder, then "iTunes."
Click "Edit" and "Preferences."
Select the "Devices" tab. Click the "Reset Sync History" button.
Select the "Info" tab. Scroll to the "Advanced" section. Click "Contacts" under the heading "Replace information on this iPhone/iPad/iPod touch."
Click "Apply." Now attempt to sync your iPhone with Outlook by connecting the smart phone to your computer using its synchronisation cable. If your contacts are still not syncing, proceed to the next section.
Open Outlook by clicking "Start," "All Programs" and "Outlook."
Click "Tools" then "Trust Center." Select "Add-ins."
If using Outlook 2003 or an older version of Outlook, click "Tools" then "Options."
Click the box next to each add-in except "iTunes Outlook add-in" under the heading "Active Application Add-Ins" to deselect the add-ins.
If using Outlook 2003 or an older version of Outlook, select the "Other" tab; then click the "Advanced Options" button.
Click "COM Add-Ins" in the "Manage" box. Click "Go." If using Outlook 2003 or an older version of Outlook, click the "COM Add-Ins" button.
Click the box next to each add-in within the "COM Add-Ins" dialogue box to deselect the add-ins. Click "OK." Now attempt to sync your iPhone with Outlook. If your contacts are still not syncing, proceed to the next section.
If using Outlook 2003 or an older version of Outlook, click the box next to each add-in except "iTunes Outlook add-in." Click "OK." Then attempt to sync your iPhone with Outlook. If your contacts are still not syncing, proceed to the next section.
Close any open programs and files including Outlook and iTunes.
Click "Start" and "Control Panel." Select "Uninstall a program" if using Windows 7 or Vista.
If using Windows XP, click "Start," "Control Panel" and "Add or Remove Programs."
Select "iTunes" and click "Uninstall" or "Remove." Follow the on-screen prompts to remove the application. Do not restart your computer if prompted to.
Select "QuickTime" next for removal; then remove the following applications in order: "Apple Software Update," "Apple Mobile Device Support," "Bonjour" and "Apple Application Support." It is important to remove the iTunes applications in the order presented in this step to prevent your system from generating error messages and encountering problems
Note: Apple Application Support is part of iTunes 9 and newer versions of the application only.
Restart your computer after removing the last application. Click the "iTunes" link the Resources section to download the latest version of the iTunes application. Click "Run" when the "Opening iTunes" dialogue box appears.
Follow the on-screen prompts to install the iTunes and the Apple Mobile Device Support component. Once the installation is finished, connect your iPhone to your computer so iTunes can set up the device and start the synchronisation process.
Before attempting to sync your iPhone with Outlook, make sure your smart phone's battery is fully charged. A low battery can cause the synchronisation process to fail and contacts to not transfer properly.