For OOS applicants, only qualified applicants receive the supplemental. I hear the cutoff is approximately 34/3.6 which seems relatively accurate. You can still be rejected post-secondary/pre-interview. ALL IS applicants who receive the secondary get interviewed.
From the secondary:
".The number of non-resident applicants who can be admitted is limited. North Carolina law (G.S. 116-143.1) requires that To qualify as a resident for tuition purposes, a person must have established legal residence (domicile) in North Carolina and maintained that legal residence for at least 12 months immediately prior to his or her classification as a resident for tuition purposes. (Physical presence in the state of North Carolina is important.)"
.To get in-state for UNC you have to be living in the state for the 12 months prior to starting school (I'm sure that this is your permanent address...so being away at college in another state does not effect it). They also ask you each address you have lived at for the last couple years (i think 3) up to application date. You will also have to show where your financial support comes from (you, parents, other) and what state the money is made in, where your bank accounts, personal belongs, cable tv accounts, etc are held.
Hope this helps