You enter n in the DSN Term field, or
You enter y in the DSN Term field, and the value in the Group Type field on page 1 of this screen is isdn, or
You enter y in the DSN Term field, and the value in the Group Type field on page 1 of this screen is tie, and the value in both the Outgoing Dial Type and Incoming Dial Type fields on page 1 of this screen is mf2/6.