Downtown Chicago is area code 312. The rest of Chicago is 773. Area code 872 is an overlay on all of the city of Chicago.
Area codes 708, 847, 224, 630, 331, 815, and 779 serve various suburbs of Chicago.
The telephone country code for the USA (and also Canada and certain nearby islands) is +1.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
US area code 872 is Chicago, IL, overlaying 312 and 773.
Springfield, IL utilizes one area code which is area code 217.
Bloomington/Normal, IL, is in area code 309.
Oak Brook, Illinois, is in area code 630 and overlay code 331.
847
area code: 630 or 331 (331 is an overlay on 630)
There is no incorporated city or town named Springfield in Utah. The urban core of Utah, including Salt Lake City, Provo, and Orem, is in area code 801 with overlay code 385. The rest of the state (the vast majority by land area) is in area code 435.
+1 618, same as East St. Louis, IL
No, not unless you have unlimited nationwide long distance.
60615 is not an area code. Area codes in the US are 3 digits and are used with telephone numbers. The postal ZIP Code 60615 is for Chicago, IL.
St. Charles, Illinois, changed from area code 708 to 630 in 1996.St. Charles was in area code 312 until the 312/708 split in 1989.
It is impossible to say without knowing what country you're asking about.