Many telephone companies maintain telephone numbers to which if a call is made will temporarily disconnect your telephone service for testing.
If your NPA is not listed, or the listing does not cover your LATA, try common numbers such as 119 (GTD5 switches) or 511.
| NPA | Telephone Number | Geography | Length of disconnection |
| 209 | 999 | Stockton, Fresno, Lodi, CA | 100 seconds |
| 281 | 325 | Houston, TX | 3 minutes |
| 313 | xxx-9994 | Ann Arbor, Dearborn, Detroit, MI (Ameritech) | 1 minute |
| 314 | 511 | Columbia, Jefferson City, St.Louis, MO | 1 minute |
| 404 | 420 | Atlanta, GA | 5 minutes |
| 405 | 953 | Enid, Oklahoma City, OK | 1 minute |
| 407 | 511 | Orlando, FL (United Telephone) | 1 minute |
| 414 | 958-0013 | Fond du Lac, Green Bay, Milwaukee, Racine, WI | 1 minute |
| 512 | 200 | Austin, Corpus Christi, TX | 1 minute |
| 516 | 480 | Hempstead, Long Island, NY | 1 minute |
| 517 | xxx-9994 | Bay City, Jackson, Lansing, MI (Ameritech) | 1 minute |
| 518 | 958 | Albany, NY | 1 minute |
| 603 | 980 | NH | |
| 614 | xxx-9894 | Columbus, Steubenville, OH | |
| 616 | xxx-9994 | Battle Creek, Grand Rapids, Kalamazoo, MI (Ameritech) | 1 minute |
| 713 | 325 | Houston, TX | 3 minutes |
| 805 | 119 | Bakersfield, Santa Barbara, CA | 3 minutes |
| 807 | 211 | Thunder Bay, Ontario | 3 minutes |
| 810 | xxx-9994 | Pontiac, Southfield, Troy, MI (Ameritech) | 1 minute |
| 832 | 325 | Houston, TX | 3 minutes |
| 906 | xxx-9994 | Marquette, Sault Ste. Marie, MI (Ameritech) | 1 minute |
| 919 | 211 or 511 | Durham, NC | 10 min – 1 hour |
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