Before we begin:

    - Importing a phone book completely replaces your existing phone book, it does not merge them.
    - You can not import from different NT versions (4.0 vs 3.51).

To import an NT 4.0 phonebook, rename phonebook.pbk on the target machine at %SystemRoot%\System32\Ras.

Copy %SystemRoot%\System32\Ras\phonebook.pbk from the source computer to the target computer.

If you have NT 3.51, the file name is rasphone.pbk. Rasphone.pbk may also be the name if you upgraded from NT 3.51.