you have saved the contacts folder as a personal folders file (.pst) - in which case you need to do the following:
1. On the File menu, click Import and Export.
Click Import from another program or file, and then click Next.
2. Click Personal Folder File (.pst), and then click Next.
3. In the File to import box, specify the path and file name of the .pst file you want to import.
4. Choose one of the following:
a)Replace duplicates with items imported
b)Existing data will be overwritten with the information in the file being imported.
c)Allow duplicates to be created. Existing data will not be overwritten, and duplicates will be added to the current Outlook folder.
d) Do not import duplicate items. Existing data will be kept, and the duplicate information in the file will not be copied to the current Outlook folder.
Then follow the remaining instructions in the Import and Export Wizard