The Illinois State Police (ISP) runs several Communications Centers, each serving 1 to 3 Troops:

• Sterling (Troops 1, 2)
• Chicago (Troop 3)
• Pontiac (Troops 4, 5, 7)
• Springfield (Troop 6 and the statewide Command Center)
• Collinsville (Troop 8)
• DuQuoin (Troops 9, 10)

ISP uses 700 and 800 MHz with VHF mobile extenders to increase communications capability when outside their vehicles.

ISPERN-Illinois State Police Emergency Radio Network

Conventional Channels - Frequencies have been moved to the WIKI as they appear to no longer (or ever heard) in use.

801 S 7th St - Springfield

Boone, Carroll, Jo Daviess, Lee, Ogle, Stephenson, Whiteside and Winnebago Counties.
Troop 1 is now patrolling I-88 in Lee and Ogle Counties as well as I-90 in Winnebago County.  Both tollways were formerly patrolled by Troop 15. (1/5/25)

Rock Island, Mercer, Henry, Bureau, Putnam and LaSalle Counties.

Serving: Cook, McHenry, Lake, DeKalb, Kane, DuPage, Kendall, Will and Grundy Counties.
Also patrols the portions of tollways I-88, I-90, I-294, I-355 and I-390 in their jurisdiction that were formerly patrolled by Troop 15. (1/5/25)

Knox, Stark, Marshall, Peoria, Woodford, Tazewell, Henderson, Warren, Hancock, McDonough, and Fulton Counties.

Livingston, McLean, Dewitt, Kankakee, Ford, and Iroquois Counties.

Adams, Schuyler, Brown, Pike, Scott, Mason, Logan, Cass, Menard, Morgan, Sangamon, and Christian Counties.

Macon, Piatt, Champain, Vermillion, Shelby, Moutlrie, Douglas, Coles and Edgar Counties.

Calhoun, Greene, Jersey, Macoupin, Montgomery, Madison, Bond, St. Clair, Clinton, Monroe and Washington Counties.
The primary function of Troopers in Troop 8 is to patrol interstates I-55, I-64, I-255, and I-270, and many rural/unincorporated areas throughout the counties
 
155.37 CSQ, Point-to-Point is available to use, for communications with agencies in St Louis MO area

ISPERN talkgroup appears to repeat mobile units using TX D156 or 67.0 PL, but not CSQ (6/24) [When acitivated by dispatch] (Base on 155.475 appears to be CSQ as to not feed back into patch]
* When VHF is activated on the talkgroup, only units using D156 transmit appear to multicast on the ISPERN talkgroup.  ISP Dispatch broadcasts as CSQ. (7/24)
700 MHz mobile extenders are no longer be in use, as portable radios are now using VHF-to-700/800 (155.505/151.16 in some areas for MX)

Cumberland, Clark, Fayette, Effingham, Jasper, Crawford, Marion, Clay, Richland, Lawrence, Wayne, Edwards, Wabash, Hamilton, and White Counties.

Jefferson, Randolph, Perry, Franklin, Jackson, Williamson, Saline, Gallatin, Union, Johnson, Pope, Hardin, Alexander, Pulaski and Massac Counties.

Troop 15 (formerly District 15) has been disbanded.  Troops 1 and 3 are now patroling the tollways in their respective jurisdictions. (1/5/25)

formerly licensed as Illinois Criminal Justice Information Authority

See IDNR Page