Sometimes, your Contacts app might not work the way you expect. If you don’t see all your contacts, review the steps in the topic 3, "Sync Your iPhone 4 with iTunes," or topic 4, "Other Sync Methods," on how to sync with your address book application. Make sure you have selected All Groups in the settings in iTunes.
TIP: If you are syncing with another contact application, such as Contacts in Gmail, make sure you select the option closest to All Contacts rather than a subset like a particular group.
When Global Address List Contacts Don’t Show Up (For Microsoft Exchange Users)
First, make sure you are connected to a Wi-Fi or 3G cellular data network.
Next, check your Exchange settings and verify you have the correct server and login information. To do so, tap the Settings button, and then scroll to and touch Mail, Contacts and Calendar. Find your Exchange account on the list and touch it to look at the settings. You may need to contact technical support at your organization to make sure your Exchange settings are correct.
