| Old New Affected Area Permissive Mandatory | | | | becomes necessary to use the new area code. If |
| 815 779 IL: Rockford, Joliet (Overlay) None | | | | you dial the old area code after the mandatory |
| 2007-03-17 | | | | date, you will reach an error recording, or worse, |
| 505 575 NM: Las Cruces, Roswell, Taos (not | | | | a wrong number. |
| Albuquerque, Santa Fe, Farmington) 2001-10-07 | | | | The Test Number is a special number (usually, |
| 2008-10-05 | | | | though not always, not charged) that allows you |
| 630 331 IL: Aurora, Hinsdale (Overlay) None TBA | | | | to test whether all the links in the chain from you |
| 618 730 IL: East St. Louis, Southern (Overlay) | | | | to a new area code are operating correctly. In |
| None TBA | | | | order for you to reach a new area code, your |
| 217 447 IL: Champaign, Springfield (Overlay) None | | | | premises equipment (office PBX, for example) |
| TBA | | | | must allow you to dial it. |
| "Permissive" refers to the date at which it | | | | Note that the test number for a new area code |
| becomes possible to use either the old or the | | | | is usually disconnected within a few months after |
| new area code. You should begin using the new | | | | the mandatory date. If you dial one of the older |
| number as soon as possible after the permissive | | | | test numbers shown here, you may reach an |
| date. | | | | ordinary subscriber. |
| "Mandatory" refers to the date at which it | | | | |