When your Mobile phone is enrolled, you are able to sync all your work contacts onto your phone.
You can choose to turn this off and on, and manage the accounts you would like to sync your contacts from.
1. Open up the Email app and select the horizontal bars on the top left
2. Select the Settings gear cog on the top right
3. Select the account you wish you sync contacts from (Exchange ActiveSync)
4. Toggle the Sync contacts on and off
You can also manage the accounts you choose to sync from in the Contacts App
1. Open the Contacts app and select the three bars on the top right
2. Select Manage Accounts
3. Toggle the accounts on and off depending which contacts you would like to sync
You can also add a contact by selecting the +(plus icon) in the contacts app and selecting the Exchange account to save contact to