Telephone Area 312. .
Prefix: +1312
This prefix is distributed within the state Illinois
The largest city in the region is Chicago
Time Zone: Central
Winter time: UTC-6
Summer time: UTC-5
Below on the map, there is indicated the largest city in the telephone area +1-312-...-.... Illinois Chicago.
In the United States, telephone numbers are divided into a country code (+1), an area code (or prefix), which is three digits long, and a subscriber number (seven digits). These are just a few examples, and there are over 300 area codes in the United States. Each code can cover both large cities and less populated areas depending on population density and telephone network distribution.
Phone numbers +1-312-YYY-YYYY
| Company | District | Major City | Prefix |
|---|---|---|---|
| Ameritech Illinois | Cook | Chicago, IL | +1-312201-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312202-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312203-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312204-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312205-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312206-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312207-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312208-SSSS |
| Cellco Partnership DBA Verizon Wireless | Cook | Northbrook, IL | +1-312209-SSSS |
| Cook | Chicago, IL | +1-312210-SSSS | |
| Ameritech Illinois | Cook | Chicago, IL | +1-312212-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312213-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312214-SSSS |
| New Cingular Wireless PCS | Cook | Wheeling, IL | +1-312215-SSSS |
| Cook | +1-312216-SSSS | ||
| United States Cellular Corp. - Illinois | Cook | Chicago, IL | +1-312217-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312218-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312220-SSSS |
| Sprint Spectrum L.p. | Cook | +1-312221-SSSS | |
| Ameritech Illinois | Cook | Chicago, IL | +1-312222-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312223-SSSS |
| Broadwing Communications | Cook | Chicago, IL | +1-312224-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312225-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312226-SSSS |
| Ameritech Illinois | Chicago, IL | +1-312227-SSSS | |
| Ameritech Illinois | Cook | Chicago, IL | +1-312228-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312229-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312230-SSSS |
| New Cingular Wireless PCS | Du Page | Roselle, IL | +1-312231-SSSS |
| American Messaging (am) | Cook | Chicago, IL | +1-312232-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312233-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312234-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312235-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312236-SSSS |
| Cellco Partnership DBA Verizon Wireless | Cook | Chicago, IL | +1-312237-SSSS |
| Broadwing Communications | Cook | Chicago, IL | +1-312238-SSSS |
| AT&T Local | Cook | Chicago, IL | +1-312239-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312240-SSSS |
| Cook | +1-312241-SSSS | ||
| Teleport Communications Group - Chicago | Cook | Chicago, IL | +1-312242-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312243-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312244-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312245-SSSS |
| New Cingular Wireless PCS | Cook | Wheeling, IL | +1-312246-SSSS |
| Globalcom-il | Cook | Chicago, IL | +1-312247-SSSS |
| Usa Mobility Wireless | Cook | Chicago, IL | +1-312249-SSSS |
| Usa Mobility Wireless | Cook | Chicago, IL | +1-312250-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312251-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312252-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312253-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312254-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312255-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312256-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312258-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312259-SSSS |
| Mcimetro Access Transmission Services LLC | Cook | Chicago, IL | +1-312260-SSSS |
| Broadwing Communications | Cook | Chicago, IL | +1-312261-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312262-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312263-SSSS |
| Broadwing Communications | Cook | Chicago, IL | +1-312264-SSSS |
| Access One | Cook | Chicago, IL | +1-312265-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312266-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312267-SSSS |
| Broadwing Communications | Cook | Chicago, IL | +1-312268-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312269-SSSS |
| Usa Mobility Wireless | Cook | Chicago, IL | +1-312271-SSSS |
| Usa Mobility Wireless | Cook | Chicago, IL | +1-312272-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312274-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312275-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312276-SSSS |
| Allegiance Telecom | Cook | Chicago, IL | +1-312277-SSSS |
| Broadwing Communications | Cook | Chicago, IL | +1-312278-SSSS |
| Mcimetro Access Transmission Services LLC | Cook | Chicago, IL | +1-312279-SSSS |
| Ameritech Illinois | Cook | Chicago, IL | +1-312280-SSSS |
| Global Crossing Local Services-il | Cook | Chicago, IL | +1-312281-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312282-SSSS |
| Global Crossing Local Services-il | Cook | Chicago, IL | +1-312283-SSSS |
| Xo Illinois | Cook | Chicago, IL | +1-312284-SSSS |
| Sprint Spectrum L.p. | Cook | Chicago, IL | +1-312285-SSSS |
| New Cingular Wireless PCS | Cook | Chicago, IL | +1-312286-SSSS |
