Apple iPhone 4s - Unify contacts

Besides entering contacts, you can:
Use your iCloud contacts: Go to Settings > iCloud, then turn on Contacts.
Import your Facebook Friends: Go to Settings > Facebook, then turn on Contacts in the
“Allow These Apps to Use Your Accounts” list. This creates a Facebook group in
Contacts.
Use your Google contacts: Go to Settings > Mail, Contacts, Calendars, tap your Google
account, then turn on Contacts.
Access a Microsoft Exchange Global Address List: Go to Settings > Mail, Contacts,
Calendars, tap your Exchange account, then turn on Contacts.
Set up an LDAP or CardDAV account to access business or school directories: Go to
Settings > Mail, Contacts, Calendars > Add Account > Other. Tap Add LDAP account or
Add CardDAV account, then enter the account information.
Sync contacts from your computer: In iTunes on your computer, turn on contact syncing
in the device info pane. For information, see iTunes Help.
Import contacts from a SIM card (GSM): Go to Settings > Mail, Contacts, Calendars >
Import SIM Contacts.
Import contacts from a vCard: Tap a .vcf attachment in an email or message.
Search a directory. Tap Groups, tap the GAL, CardDAV, or LDAP directory you want to
search, then enter your search. To save a person’s info to your contacts, tap Add Contact.
Show or hide a group. Tap Groups, then select the groups you want to see. This button
appears only if you have more than one source of contacts.
Update your contacts using Twitter, Facebook, and Sina Weibo. Go to Settings >
Twitter, Settings > Facebook, or Settings > Sina Weibo, then tap Update Contacts. This
updates contact photos and social media account names in Contacts.
Unify contacts
When you have contacts from multiple sources, you might have multiple entries for the
same person. To keep redundant contacts from appearing in your All Contacts list, contacts
from different sources that have the same name are linked and displayed as a single unified
contact. When you view a unified contact, the title Unified Info appears.