Synchronizing the customer and supplier contacts from your companies ERP or CRM software into Exchange is not always built-in or supported by your vendor.
We’ve faced a similar problem and developed a solution to import and synchronize contact information e.g. as a CSV or Excel file with the corporate Exchange server and the Global Address List (GAL).
Now it is easy to search for a customer’s phone number on the go or write an email to a contact that is not in your personal Outlook address book.