| General Information | |
|---|---|
| Country | United States |
| State/Province | Illinois |
| Major City | Lombard |
| Time Zone | Central (UTC-06:00) |
| Current Local Time | 03:08 |
| Prefix | County | Primary City |
|---|---|---|
| 331-200 | Cook | Hanover Park |
| 331-201 | Dupage | Downers Grove |
| 331-202 | Dupage | Elmhurst |
| 331-203 | Kane | Aurora |
| 331-205 | Kane | Aurora |
| 331-206 | Kane | Aurora |
| 331-207 | Kendall | Yorkville |
| 331-208 | Kane | Aurora |
| 331-209 | Dupage | Elmhurst |
| 331-210 | Kane | Geneva |
| 331-212 | Kane | Aurora |
| 331-213 | Dupage | Naperville |
| 331-214 | Dupage | Downers Grove |
| 331-215 | Dupage | Naperville |
| 331-216 | Kendall | Oswego |
| 331-218 | Dupage | Wheaton |
| 331-220 | Kane | Aurora |
| 331-221 | Dupage | Elmhurst |
| 331-222 | Kane | Geneva |
| 331-223 | Kane | Geneva |
| 331-225 | Dupage | Elmhurst |
| 331-228 | Kane | Geneva |
| 331-229 | Dupage | Naperville |
| 331-234 | Kane | Sugar Grove |
| 331-240 | Dupage | West Chicago |
| 331-245 | Cook | Hanover Park |
| 331-248 | Kane | Geneva |
| 331-250 | Kane | Aurora |
| 331-251 | Dupage | Downers Grove |
| 331-253 | Will | Homer Glen |
| 331-254 | Kane | Sugar Grove |
| 331-256 | Kane | Aurora |
| 331-262 | Kane | Aurora |
| 331-276 | Kane | Geneva |
| 331-281 | Dupage | Naperville |
| 331-301 | Kane | Aurora |
| 331-302 | Kane | Aurora |
| 331-303 | Kane | Elburn |
| 331-304 | Cook | Hanover Park |
| 331-305 | Dupage | Naperville |
| 331-307 | Dupage | Lombard |
| 331-308 | Cook | Hanover Park |
| 331-310 | Kane | Big Rock |
| 331-318 | Will | Homer Glen |
| 331-321 | Dupage | Dupage |
| 331-330 | Kendall | Montgomery |
| 331-332 | Dupage | Naperville |
| 331-333 | Dupage | Naperville |
| 331-422 | Kane | Geneva |
| 331-425 | Kane | Aurora |