Appeal from the Circuit Court of Cook County No. 01 CH 12217 Honorable Donald J. O'Brien, Judge Presiding.
 The opinion of the court was delivered by: Justice Cahill
 We consider whether defendant, the Illinois Department of Central Management Services (CMS), had the authority to promulgate a rule that wireless carriers could recover no more than 100% of a surcharge. The surcharge is to be collected and remitted to a fund established to defray carriers' expenses in establishing 9-1-1 emergency service. The issue and the validity of the rule arises because the Wireless Emergency Telephone Safety Act (Act) (50 ILCS 751/1 et seq. (West 2002)) allows wireless carriers to receive up to 125% of the amount collected in surcharges. The plaintiffs filed a complaint in the circuit court in 2001, claiming the CMS 100% rule conflicts with the Act. The circuit court granted summary judgment in favor of plaintiffs and CMS appeals.
 The Act, which became effective in July 1999, provides, "it is in the public interest to promote the use of wireless 9-1-1 and wireless enhanced 9-1-1 (E9-1-1) service in order to save lives and protect the property of the citizens of the State of Illinois." 50 ILCS 751/5 (West 2002). The legislature recognized:
 "[W]ireless carriers *** require adequate funding to recover the costs of designing, purchasing, installing, testing, and operating enhanced facilities, systems, and services necessary to comply with the wireless E9-1-1 requirements mandated by the Federal Communications Commission [(FCC)] and to maximize the availability of wireless E9-1-1 services throughout the State of Illinois." 50 ILCS 751/5 (West 2002). Section 5 of the Act encourages wireless carriers to provide 9-1-1 services "that will assist public safety agencies in determining the caller's approximate location and wireless telephone number" and to reimburse wireless carries for the costs they incur. 50 ILCS 751/5 (West 2002).
 Section 17 of the Act establishes a surcharge on telephone bills to reimburse carriers' costs:
 "(a) *** [E]ach wireless carrier shall impose a monthly wireless carrier surcharge per *** connection that either has a telephone number within an area code assigned to Illinois *** or has a billing address in this State. ***
 (b) *** [A] wireless carrier shall, within 45 days of collection, remit *** to the State Treasurer the amount of the wireless carrier surcharge collected from each subscriber. Of the amounts remitted under this subsection, the State Treasurer shall deposit one-third into the Wireless Carrier Reimbursement Fund [(WCRF)] ***." 50 ILCS 751/17(a), (b) (West 2002). The amount of the surcharge is to be set by a Wireless Enhanced 9-1-1 Board, but the charge may not exceed $.75 per month per connection. 50 ILCS 751/15(c) (West 2002).
 Section 30 of the Act establishes the WCRF as a separate fund of the State treasury:
 "Moneys in the [WCRF] may be used, subject to appropriation, only to reimburse wireless carriers for all [emphasis added] of their costs incurred in complying with the *** [FCC] wireless enhanced 9-1-1 service mandates ***. This reimbursement may include, but need not be limited to, the cost of designing, upgrading, purchasing, leasing, programming, installing, testing, and maintaining necessary data, hardware, and software and associated operating and administrative costs and overhead." 50 ILCS 751/30 (West 2002).
 Section 35 outlines the procedures to be followed by carriers seeking reimbursement under the Act:
 "To recover costs from the [WCRF], the wireless carrier shall submit sworn invoices to [CMS]. In no event may any invoice for payment be approved for (i) costs that are not related to compliance with the requirements established by the wireless enhanced 9-1-1 mandates of the [FCC], (ii) costs with respect to any wireless enhanced 9-1-1 service that is not operable at the time the invoice is submitted, or (iii) costs of any wireless carrier exceeding 125% of the wireless emergency services charges remitted to the [WCRF] by the wireless carrier *** unless the wireless carrier received prior approval for the expenditures from [CMS]." 50 ILCS 751/35 (West 2000). Section 35 further provides, "[CMS] shall adopt rules to govern the reimbursement process." 50 ILCS 751/35 (West 2002).
 CMS promulgated an administrative rule governing reimbursements under the Act:
 "Moneys in the WCRF may be used, subject to appropriation, only to reimburse Carriers for costs incurred in complying with the applicable provisions of FCC wireless enhanced 9-1-1- service mandates and to pay Administrative Costs. In no event shall ...